Semtech (SMTC) 10-Q 30 Nov 16 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Oct. 30, 2016	Nov. 25, 2016
Entity Information [Line Items]
Document Type	10-Q
Document Period End Date	Oct. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Entity Registrant Name	SEMTECH CORP
Entity Central Index Key	88,941
Current Fiscal Year End Date	--01-29
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		65,636,833

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Net sales	$ 137,185	$ 115,810	$ 404,241	$ 371,610
Cost of sales	56,120	46,226	162,877	148,050
Gross profit	81,065	69,584	241,364	223,560
Operating costs and expenses:
Selling, general and administrative	35,116	30,747	101,654	102,383
Product development and engineering	25,600	26,855	77,097	84,771
Intangible amortization	6,286	6,308	19,017	18,648
Gain on disposition of business operations	(25,036)	0	(25,036)	0
Changes in the fair value of contingent earn-out obligations	0	(14,186)	(162)	(13,618)
Restructuring charge	0	962	0	4,526
Total operating costs and expenses	41,966	50,686	172,570	196,710
Operating income	39,099	18,898	68,794	26,850
Interest expense, net	(1,890)	(1,964)	(5,857)	(5,698)
Non-operating expense, net	(690)	(777)	(871)	(1,152)
Income before taxes	36,519	16,157	62,066	20,000
Provision for taxes	5,743	5,453	15,424	9,750
Net income	$ 30,776	$ 10,704	$ 46,642	$ 10,250
Earnings per share:
Basic (in dollars per share)	$ 0.47	$ 0.16	$ 0.71	$ 0.16
Diluted (in dollars per share)	$ 0.46	$ 0.16	$ 0.71	$ 0.15
Weighted average number of shares used in computing earnings per share:
Basic (in shares)	65,549	65,117	65,331	65,920
Diluted (in shares)	66,206	65,217	65,899	66,251

Condensed Consolidated Stateme3

Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Net income	$ 30,776	$ 10,704	$ 46,642	$ 10,250
Other comprehensive (loss) income:
Unrealized (loss) gain on foreign currency cash flow hedges, net of tax	(422)	0	321	0
Adjustment for net gains realized and included in net income, net of tax	(88)	0	(546)	0
Change in unrealized loss on interest rate cap, net of tax	0	0	0	(33)
Adjustment for net (loss) income realized and included in interest expense, net of tax	(37)	129	48	299
Change in employee benefit plans, net of tax of $967 for the three and nine months ended October 30, 2016	(3,429)	0	(3,429)	0
Other changes to comprehensive income	129	0	129	0
Other comprehensive (loss) income, net of tax	(3,847)	129	(3,477)	266
Total comprehensive income	$ 26,929	$ 10,833	$ 43,165	$ 10,516

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Oct. 30, 2016	Oct. 30, 2016
Statement of Comprehensive Income [Abstract]
Change in employee benefit plans, tax	$ 967	$ 967

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Current assets:
Cash and cash equivalents	$ 297,939	$ 211,810
Accounts receivable, less allowances of $8,103 at October 30, 2016 and $7,793 at January 31, 2016	59,193	44,132
Inventories	62,679	63,875
Prepaid taxes	6,982	5,236
Other current assets	11,917	16,168
Total current assets	438,710	341,221
Non-current assets:
Property, plant and equipment, net of accumulated depreciation of $156,549 at October 30, 2016 and $143,782 at January 31, 2016	95,547	101,006
Deferred tax assets	8,711	7,354
Goodwill	329,703	329,703
Other intangible assets, net	68,064	88,430
Other assets	60,314	43,803
TOTAL ASSETS	1,001,049	911,517
Current liabilities:
Accounts payable	43,931	35,486
Accrued liabilities	43,731	41,204
Deferred revenue	11,026	8,628
Current portion - long-term debt	19,094	18,569
Total current liabilities	117,782	103,887
Non-current liabilities:
Deferred tax liabilities	22,462	6,802
Long term debt, less current portion	228,795	239,177
Other long-term liabilities	46,115	33,600
Stockholders’ equity:
Common stock, $0.01 par value, 250,000,000 shares authorized, 78,136,144 issued and 65,598,116 outstanding on October 30, 2016 and 78,136,144 issued and 64,998,368 outstanding on January 31, 2016	785	785
Treasury stock, at cost, 12,538,028 shares as of October 30, 2016 and 13,137,776 shares as of January 31, 2016	(256,138)	(266,175)
Additional paid-in capital	384,150	379,508
Retained earnings	459,922	413,280
Accumulated other comprehensive (loss) income	(2,824)	653
Total stockholders’ equity	585,895	528,051
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 1,001,049	$ 911,517

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts, receivables	$ 8,103	$ 7,793
Accumulated depreciation	$ 156,549	$ 143,782
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	78,136,144	78,136,144
Common stock, shares outstanding	65,598,116	64,998,368
Treasury stock, shares	12,538,028	13,137,776

Condensed Consolidated Stateme7

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015
Cash flows from operating activities:
Net income	$ 46,642	$ 10,250
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and impairments	35,506	36,534
Accretion of deferred financing costs and debt discount	492	1,054
Deferred income taxes	15,659	4,366
Share-based compensation	21,198	13,398
(Gain) loss on disposition of business operations and assets	(24,988)	23
Earn-out liabilities	(162)	(13,618)
Environmental reserve	(68)	2,855
Changes in assets and liabilities:
Accounts receivable, net	(15,994)	14,577
Inventories	1,302	2,694
Prepaid expenses and other assets	(11,785)	5,975
Accounts payable	6,775	677
Accrued liabilities	8,885	(15,631)
Deferred revenue	3,300	1,033
Income taxes payable and prepaid taxes	(7,875)	2,086
Other liabilities	5,807	1,343
Net cash provided by operating activities	84,694	67,616
Cash flows from investing activities:
Purchase of property, plant and equipment	(13,754)	(10,705)
Acquisitions, net of cash acquired	0	(44,432)
Purchases of other investments	(3,248)	(5,230)
Proceeds from disposition of business operations	32,045	0
Proceeds from sale of equity investments	555	5,261
Net cash provided by (used in) investing activities	15,598	(55,106)
Cash flows from financing activities:
Borrowings under line of credit	0	35,000
Payment for employee share-based compensation payroll taxes	(5,928)	(6,070)
Proceeds from exercises of stock options	1,678	3,965
Repurchase of outstanding common stock	(539)	(57,311)
Payment of long term debt	(9,374)	(26,063)
Net cash used in financing activities	(14,163)	(50,479)
Net increase (decrease) in cash and cash equivalents	86,129	(37,969)
Cash and cash equivalents at beginning of period	211,810	230,328
Cash and cash equivalents at end of period	$ 297,939	$ 192,359

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Oct. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Nature of Business Semtech Corporation (together with its subsidiaries, the “Company” or “Semtech”) is a global supplier of analog and mixed-signal semiconductor products. The end-customers for the Company’s products are primarily original equipment manufacturers (“OEM’s”) that produce and sell electronics. The Company designs, develops and markets a wide range of products for commercial applications, the majority of which are sold into the enterprise computing, communications, high-end consumer and industrial end-markets. Enterprise Computing: datacenters, passive optical networks, desktops, notebooks, servers, graphic boards, monitors, printers and other computer peripherals. Communications: base stations, optical networks, carrier networks, switches and routers, cable modems, wireless LAN and other communication infrastructure equipment. High-End Consumer: handheld products, smartphones, wireless charging, set-top boxes, digital televisions, tablets, digital video recorders and other consumer equipment. Industrial: video broadcast equipment, automated meter reading, Internet of Things (“IoT”), smart grid, wireless charging, military and aerospace, medical, security systems, automotive, industrial and home automation, video security and surveillance and other industrial equipment. Fiscal Year The Company reports results on the basis of 52 and 53 week periods and ends its fiscal year on the last Sunday in January. The other quarters generally end on the last Sunday of April, July and October. All quarters consist of 13 weeks except for one 14 -week period in the fourth quarter of 53 -week years. The third quarter of fiscal years 2017 and 2016 each consisted of 13 weeks. Principles of Consolidation The accompanying interim unaudited condensed consolidated financial statements have been prepared by the Company, in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and the instructions to quarterly report on Form 10-Q under the Securities Exchange Act of 1934, as amended, and Article 10 of Regulation S-X. In the opinion of the Company, these unaudited statements contain all adjustments (consisting of normal recurring adjustments) necessary to present fairly, in all material respects, the financial position of the Company for the interim periods presented. All significant intercompany balances have been eliminated. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, and the Company believes that the included disclosures are adequate to make the information presented not misleading. The Company evaluated all subsequent events through the date these interim unaudited condensed consolidated financial statements were issued. On March 4, 2015, the Company completed the acquisition of Triune Systems, L.L.C. (“Triune”). On January 13, 2015, the Company completed the acquisition of selected assets from EnVerv, Inc. (“EnVerv”). The interim unaudited condensed consolidated financial statements include the results of income of Triune and EnVerv commencing as of the acquisition dates. These interim unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended January 31, 2016 . The results reported in these interim unaudited condensed consolidated financial statements should not be regarded as indicative of results that may be expected for any subsequent period or for the entire year. Segment Information The Company’s Chief Executive Officer (“CEO”) has been identified as the Chief Operating Decision Maker (“CODM”) as defined by guidance regarding segment disclosures (see Note 14 for further discussion). In fiscal year 2016, the Company updated its assessment of its operations in light of its restructuring efforts (see Note 17 for further discussion) and strategic business decisions. Based on this assessment, at that time the Company had identified five operating segments in total. Four of the operating segments aggregated into one reportable segment, the Semiconductor Products Group. The remaining operating segment, the Systems Innovation Group (shown as “All others”), could not be aggregated with the other operating segments and did not meet the criteria for a separate reportable segment as defined by the guidance regarding segment disclosure. As a result, the financial activity associated with the Systems Innovation Group was reported separately from the Company’s Semiconductor Products Group. This separate reporting was included in the “All others” category. On August 5, 2016, the Company completed its divestiture of its Snowbush Intellectual Property (“Snowbush IP”) business (previously part of the Company’s Systems Innovation Group) to Rambus Inc. (“Rambus”) for a purchase price of $32.0 million in cash along with the opportunity to receive additional payments from Rambus through 2022 based upon a percentage of sales by Rambus of new products expected to be developed by Rambus from the disposed assets. Beginning in the third quarter of fiscal year 2017, the Company no longer has a Systems Innovation Group or an “All others” category, and therefore has only four operating segments that aggregate into one reportable segment, the Semiconductor Products Group. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Derivatives and Hedging Activities Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 815, Derivatives and Hedging, provides the disclosure requirements for derivatives and hedging activities with the intent to provide users of financial statements with an enhanced understanding of: (a) how and why an entity uses derivative instruments, (b) how the entity accounts for derivative instruments and related hedged items, and (c) how derivative instruments and related hedged items affect an entity’s financial position, financial performance, and cash flows. Further, qualitative disclosures are required that explain the Company’s objectives and strategies for using derivatives, as well as quantitative disclosures about the fair value of and gains and losses on derivative instruments, and disclosures about credit-risk-related contingent features in derivative instruments. As required by ASC 815, the Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. In accordance with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. Recent Accounting Pronouncements On August 26, 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-15, “Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments.” The primary purpose of this ASU is to reduce the diversity in practice that has resulted from the lack of consistent principles on this topic. This ASU is effective for fiscal years beginning after December 15, 2017. This ASU will be effective for the Company as of the beginning of Fiscal 2019. Early adoption is permitted in any interim or annual period. The Company is in the process of determining the impact of the adoption of this guidance on its consolidated financial statements or notes thereto; however, it does not anticipate that the new guidance will have a significant impact on its consolidated financial statements. In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842), which will require that substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The new standard also will result in enhanced quantitative and qualitative disclosures, including significant judgments made by management, to provide greater insight into the extent of revenue and expense recognized and expected to be recognized from existing leases. The standard requires modified retrospective adoption and will be effective December 15, 2018, with early adoption permitted. The Company does not expect the adoption of this update to have a material impact on its consolidated financial statements. In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330) Related to Simplifying the Measurement of Inventory which will apply to all inventory except inventory that is measured using last-in, first-out (“LIFO”) or the retail inventory method. Inventory measured using first-in, first-out or average cost is covered by the new amendments. Inventory within the scope of the new guidance should be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. Subsequent measurement is unchanged for inventory measured using LIFO or the retail inventory method. The amendments will take effect for public business entities for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The new guidance should be applied prospectively, and earlier application is permitted as of the beginning of an interim or annual reporting period. The Company is currently assessing the impact this update will have on its consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which will require an entity to recognize revenue from the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance addresses, in particular, contracts with more than one performance obligation, as well as the accounting for some costs to obtain or fulfill a contract with a customer, and provides for additional disclosures with respect to revenues and cash flows arising from contracts with customers. Public entities are required to apply the amendments on either a full- or modified-retrospective basis for annual periods beginning after December 15, 2017 and for interim periods within those annual periods. This update will be effective for the Company beginning in the first quarter of fiscal year 2019. Early adoption is not permitted. The Company is currently assessing the basis of adoption and evaluating the impact of the adoption of the update on its consolidated financial statements.

Acquisitions

Acquisitions	9 Months Ended
	Oct. 30, 2016
Business Combinations [Abstract]
Business Combination Disclosure	Acquisitions Triune Systems, L.L.C On March 4, 2015 , the Company acquired Triune Systems, L.L.C. , a privately-held supplier of isolated switching, wireless charging and power management platforms targeted at, among other things, high and low power, high efficiency applications. Under the terms of the purchase agreement, the Company acquired all of the outstanding equity interest in Triune for a guaranteed minimum purchase price of $45.0 million consisting of $35.0 million in cash paid at closing, with an additional cash consideration of $10.0 million of which $9.5 million was paid in September 2015 and $0.5 million was paid in the second quarter of fiscal year 2017. In March 2015, the Company borrowed $35.0 million under its prior revolving line of credit in connection with this acquisition (see Note 10 for discussion regarding Credit Facilities). Subject to achieving certain future financial goals (“Triune Earn-out”), up to $70.0 million of contingent consideration will be paid over the next two years if certain net revenue targets are achieved in each of fiscal years 2017 and 2018. An additional payment of up to $16.0 million will be paid after fiscal year 2018 if certain cumulative net revenue and contribution margin targets are achieved. The Triune Earn-out targets for fiscal year 2016 were not met and the Company does not expect the fiscal year 2017 or 2018 targets to be achieved. The fair value of the Triune Earn-out liability was zero as of October 30, 2016 . See Notes 7 and 12 . The Triune business meets the definition of a business and is accounted for under the acquisition method of accounting in accordance with the FASB’s ASC Topic 805, Business Combinations. The purchase price allocation for the Triune acquisition was finalized in the second quarter of fiscal year 2016. Total acquisition consideration has been allocated to the acquired tangible and intangible assets and assumed liabilities of Triune based on their respective estimated fair values as of the acquisition date. Acquisition-related transaction costs are not included as a component of consideration transferred, but are accounted for as an expense in the period in which the costs are incurred. Any excess of the acquisition consideration over the fair value of the assets acquired and liabilities assumed has been allocated to goodwill. The goodwill resulted from expected synergies from the transaction, including complementary products that will enhance the Company’s overall product portfolio, and opportunities within new markets. The Company expects that all such goodwill will be deductible for tax purposes. The Company’s allocation of the total purchase price for Triune is summarized below: (in thousands) At March 4, 2015 Current assets $ 877 Property, plant, and equipment, net 226 Core technologies 10,000 Customer relationships 2,000 Goodwill 49,384 Current liabilities (1,287 ) Earn-out liability (16,200 ) Total acquisition consideration $ 45,000 Triune’s technology complemented the portfolio of products offered in the Company’s legacy Power and High-Reliability reporting unit. The Company concluded that the Triune and legacy Power and High-Reliability components should be aggregated and deemed a single reporting unit after considering similarities among different economic characteristics such as concentration of key customers, unit selling price decreases, increased competitors due to market expansion and chain of command of the newly acquired business. Net revenues and earnings attributable to Triune since the acquisition date have not been material. Pro forma results of operations have not been presented as Triune’s annual operating results are not material to the Company’s unaudited condensed consolidated financial statements. EnVerv, Inc. On January 13, 2015 , the Company paid $4.9 million to acquire selected assets from EnVerv , Inc., a privately-held supplier of power line communications and Smart Grid solutions targeted at advanced metering infrastructure, home energy management systems and IoT applications. The Company has concluded that the acquired assets constituted a business and accordingly accounted for this transaction as a business combination. The purchase price allocation for the EnVerv acquisition was finalized in the first quarter of fiscal year 2016. Total acquisition consideration has been allocated to the acquired tangible and intangible assets and assumed liabilities based on their respective estimated fair values as of the acquisition date. The excess of the acquisition consideration over the fair value of assets acquired and liabilities assumed has been allocated to goodwill. As of January 25, 2015 , $1.4 million of the total acquisition consideration has been allocated to core technologies and $3.4 million has been allocated to goodwill. The remaining balance has been allocated to acquired tangible assets and assumed liabilities. The Company expects that all such goodwill will be deductible for tax purposes. Net revenues and earnings attributable to EnVerv since the acquisition date have not been material. Pro forma results of operations have not been presented as EnVerv’s annual operating results are not material to the Company’s unaudited condensed consolidated financial statements.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Oct. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per Share The computation of basic and diluted earnings per common share is as follows: Three Months Ended Nine Months Ended (in thousands, except per share amounts) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Net income $ 30,776 $ 10,704 $ 46,642 $ 10,250 Weighted average common shares outstanding - basic 65,549 65,117 65,331 65,920 Dilutive effect of options and restricted stock units 657 100 568 331 Weighted average common shares outstanding - diluted 66,206 65,217 65,899 66,251 Basic earnings per common share $ 0.47 $ 0.16 $ 0.71 $ 0.16 Diluted earnings per common share $ 0.46 $ 0.16 $ 0.71 $ 0.15 Anti-dilutive shares not included in the above calculations 989 3,728 1,498 2,392 Basic earnings per common share is computed by dividing net income available to common stockholders by the weighted-average number of shares of common stock outstanding during the reporting period. Diluted earnings per common share incorporate the incremental shares issuable, calculated using the treasury stock method, upon the assumed exercise of stock options and the vesting of restricted stock.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Oct. 30, 2016
Revenue Recognition [Abstract]
Revenue Recognition	Revenue Recognition The Company recognizes product revenue when persuasive evidence of an arrangement exists, delivery has occurred, the fee is fixed or determinable and collectability is probable. Recovery of costs associated with product design and engineering services are recognized during the period in which services are performed. The product design and engineering recovery, when recognized, will be reported as a reduction to product development and engineering expense. Historically, these recoveries have not exceeded the cost of the related development efforts. The Company includes revenue related to technology licenses as part of “Net sales.” Historically, revenue from these arrangements has not been significant though it is part of the Company’s recurring ordinary business. The Company defers revenue recognition on shipment of products to certain customers, principally distributors, under agreements which provide for limited pricing credits or return privileges, until these products are sold through to end users or the return privileges lapse. For sales subject to certain pricing credits or return privileges, the amount of future pricing credits or inventory returns cannot be reasonably estimated given the relatively long period in which a particular product may be held by the customer. Therefore, the Company has concluded that sales to customers under these agreements are not fixed and determinable at the date of the sale and revenue recognition has been deferred. The Company estimates the deferred gross margin on these sales by applying an average gross profit margin to the actual gross sales. The average gross profit margin is calculated for each category of material using standard costs which is expected to approximate actual costs at the date of sale. The estimated deferred gross margins on these sales, where there are no outstanding receivables, are recorded on the condensed consolidated balance sheets under the heading of “Deferred revenue.” The Company records a provision for estimated sales returns in the same period as the related revenues are recorded. The Company bases these estimates on historical sales returns and other known factors. Actual returns could be different from Company estimates and current provisions for sales returns and allowances, resulting in future charges to earnings. There were no significant impairments of deferred cost of sales in the third quarters of fiscal years 2017 or 2016 . The Company records a provision for sales rebates in the same period as the related revenues are recorded. These estimates are based on sales activity during the period. Actual rebates given could be different from our estimates and current provisions for sales rebates, resulting in future charges to earnings. The estimated sales rebates for sales activity during the period where there are no outstanding receivables are recorded on the condensed consolidated balance sheets under the heading of “Accrued liabilities.” The portion of the estimated sales rebate where there are outstanding receivables is recorded on the balance sheet as a reduction to accounts receivable.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Oct. 30, 2016
Share-based Compensation [Abstract]
Share-Based Compensation	Share-Based Compensation Financial Statement Effects and Presentation . The following table summarizes pre-tax, share-based compensation included in the unaudited condensed consolidated statements of income for the three and nine months ended October 30, 2016 and October 25, 2015 . Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Revenue offset $ 3,669 $ — $ 3,669 $ — Cost of sales 360 197 1,108 1,071 Selling, general and administrative 3,965 2,933 12,001 6,006 Product development and engineering 1,401 1,987 4,420 6,320 Share-based compensation $ 9,395 $ 5,117 $ 21,198 $ 13,397 Net change in share-based compensation capitalized into inventory $ 124 $ (233 ) $ 106 $ 45 Grant Date Fair Values and Underlying Assumptions: Contractual Terms The Company uses the Black-Scholes pricing model to value stock options. The estimated fair value of restricted stock units, for which vesting is not linked to a market condition, is calculated based on the market price of the Company’s common stock on the date of grant. For restricted stock units that vest according to a market condition, the Company uses a Monte Carlo simulation model to value the award. Some of the restricted stock units granted in the first nine months of fiscal year 2017 and prior years are classified as liabilities rather than equity. For grants classified as equity, share-based compensation is measured at the grant date, based on the fair value of the award, and is recognized as an expense over the grantee’s requisite service period. For grants classified as liabilities, share-based compensation is measured at fair value at the end of each reporting period until the date of settlement, and is recognized as an expense over the grantee’s requisite service period. Expected volatilities are based on historical volatility using daily and monthly stock price observations. The following table summarizes the assumptions used in the Black-Scholes model to determine the fair value of stock options granted in the three and nine months ended October 30, 2016 and October 25, 2015 , respectively: Three Months Ended Nine Months Ended October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Expected lives, in years 4.2 4.2 4.1 - 4.5 4.2 - 4.3 Estimated volatility 32% 32% 32% 29% - 32% Dividend yield — — — — Risk-free interest rate 1.0% 1.3% 1.1% - 1.3% 1.24% - 1.29% Weighted average fair value on grant date $7.10 $4.80 $5.67 $6.09 Stock Options . The Company has historically granted stock options to both employees and non-employee directors. The fair values of these grants were measured on the grant date. The grant dates for these awards are equal to the measurement date. These awards are valued as of the measurement date and recognized as an expense over the requisite vesting period (typically 3 - 4 years). The following table summarizes the activity for stock options for the nine months ended October 30, 2016 : (in thousands, except for per share amounts) Number of Shares Weighted Average Exercise Price (per share) Aggregate Intrinsic Value Aggregate Unrecognized Compensation Number of Shares Exercisable Weighted Average Contractual Term (in years) Balance at January 31, 2016 1,507 $ 25.18 $ 962 $ 3,748 775 Options granted 356 20.58 Options exercised (86 ) 19.17 482 Options cancelled/forfeited (95 ) 22.10 Balance at October 30, 2016 1,682 $ 24.69 $ 3,419 $ 3,796 902 Exercisable at October 30, 2016 902 $ 26.30 $ 873 2.3 Performance-Based Restricted Stock Units . The Company grants performance-based restricted stock units to select employees. These awards have a performance condition in addition to a service condition. The performance metrics are determined based on a pre-defined cumulative three -year performance of the Company’s net revenue and non-GAAP operating income measured against internal goals. The performance award which is granted in any fiscal year will be tied to the Company’s performance of that fiscal year and the succeeding two fiscal years. The performance award recipients must be employed for the entire three -year period, which is the explicit service and requisite service period, and be an active employee at the time of vesting of the awards (cliff vesting at the end of the third year). Under the terms of these awards, assuming the highest performance level of 200% with no cancellations due to forfeitures, the maximum number of shares that can be earned would be 582,032 shares and an additional 582,032 shares would be settled in cash. The Company would have a liability accrued under “Other liabilities” within the condensed consolidated balance sheets equal to the value of 582,032 shares on the settlement date, which would be settled in cash. Only cash performance-based restricted stock unit awards are classified as liabilities and the value of these awards is re-measured at each reporting date. At October 30, 2016 , the performance metrics associated with the outstanding awards issued in fiscal years 2017 and 2016 are expected to be met at a level which would result in a grant at 190% and 0% of target, respectively. In the first quarter of fiscal year 2016, the Company granted performance-based vesting restricted stock units to select employees as part of the EnVerv acquisition. These awards have a performance condition in addition to a service condition. The performance metrics are determined based on a pre-defined net revenue target. In addition to the performance vesting condition, these awards have a requisite four year vesting term (which is also the requisite vesting period) whereby 25% will vest, subject to attainment of the performance condition, on each anniversary of the grant date. Under the terms of these awards, assuming the highest performance level of 100% with no cancellations due to forfeitures, the maximum number of shares that can be earned would be 24,000 . At October 30, 2016 , the performance metrics associated with the outstanding awards issued in fiscal year 2016 are not expected to be met which would result in none of the shares being issued. The performance-based restricted stock units are valued as of the measurement date and expense is recognized on a straight line basis for the awards expected to vest based on the probability of attainment of the performance condition for each separately vesting portion of the award. The following table summarizes the activity for performance-based restricted stock units for the nine months ended October 30, 2016 : Subject to Share Settlement Subject to Cash Settlement Weighted Average Grant Date Fair Value (per unit) Aggregate Unrecognized Compensation Weighted Average Period Over Which Expected to be Recognized (in years) (in thousands, except for per unit amounts) Total Units Units Units Recorded Liability Balance at January 31, 2016 384 203 181 $ 237 $ 26.57 $ 1,925 1.5 Performance-based units granted 231 116 115 17.51 Performance-based units vested — — — — Performance-based units cancelled/forfeited (12 ) (6 ) (6 ) 17.51 Change in liability 621 Balance at October 30, 2016 603 313 290 $ 858 $ 23.29 $ 7,989 1.3 Changes in the liability associated with performance-based restricted stock units, which is recorded in “Other long-term liabilities” within the condensed consolidated balance sheets, is due to changes in proportionate vesting and estimated forfeitures, re-measurement adjustments related to changes in market value and changes in the expected performance results. Market Performance Restricted Stock Units. On February 26, 2014, the Company granted its CEO restricted stock units with a market performance condition. The award is eligible to vest during the period commencing February 26, 2014 and ending February 26, 2019 (the “Performance Period”) as follows: 30% of the restricted stock units covered by the award will vest if, during any consecutive 120 calendar day period that commences and ends during the Performance Period, the average per-share closing price of the Company’s common stock equals or exceeds $35.00 (“Tranche 1”) and the award will vest in full if, during any consecutive 120 calendar day period that commences and ends during the Performance Period, the average per-share closing price of the Company’s common stock equals or exceeds $40.00 (“Tranche 2”). The award will also vest if a majority change in control of the Company occurs during the Performance Period and, in connection with such event, the Company’s stockholders become entitled to receive per-share consideration having a value equal to or greater than $40.00 . The fair value of the awards was determined to be $17.26 and $14.88 for Tranche 1 and Tranche 2, respectively, on the grant date by application of the Monte Carlo simulation model. The following table summarizes the activity for market performance restricted stock units for the nine months ended October 30, 2016 : Weighted Average Grant Date Fair Value (per unit) Aggregate Unrecognized Compensation Period Over Which Expected to be Recognized (in years) (in thousands, except for per unit amounts) Total Units Balance at January 31, 2016 220 $ 15.59 $ 143 0.1 Market performance units granted — — Market performance units vested — — Market performance units cancelled/forfeited — — Balance at October 30, 2016 220 $ 15.59 $ — 0.0 Restricted Stock Units, Employees . The Company grants restricted stock units to employees which are expected to be settled with stock. The grant date for these awards is equal to the measurement date. These awards are valued as of the measurement date and recognized as an expense over the requisite vesting period (typically 4 years). The following table summarizes the employees’ restricted stock unit activity for the nine months ended October 30, 2016 : (in thousands, except for per unit amounts) Number of Units Weighted Average Grant Date Fair Value (per unit) Aggregate Intrinsic Value (1) Aggregate Unrecognized Compensation Weighted Average Period Over Which Expected to be Recognized (in years) Balance at January 31, 2016 2,032 $ 23.70 $ 35,692 2.4 Restricted stock units granted 1,147 21.76 Restricted stock units vested (714 ) 25.28 $ 16,134 Restricted stock units forfeited (270 ) 20.77 Balance at October 30, 2016 2,195 $ 22.53 $ 41,348 2.6 (1) Reflects the value of Semtech Corporation stock on the date that the restricted stock unit vested. Restricted Stock Units, Cash Settled, Non-Employee Directors . The Company maintains a compensation program pursuant to which restricted stock units are granted to the Company’s directors that are not employed by the Company or any of its subsidiaries. In June 2015, the Company changed its director compensation program so that a portion of the restricted stock units granted under the program would be settled in cash and a portion would be settled in stock. Restricted stock units awarded under the program are scheduled to vest on the earlier of (i) one year after the grant date or (ii) the day immediately preceding the annual meeting of shareholders in the year following the grant. The portion of a restricted stock unit award under the program that is to be settled in cash will, subject to vesting, be settled when the director who received the award separates from the board of directors. The portion of a restricted stock unit award under the program that is to be settled in stock will, subject to vesting, be settled promptly following vesting. There were no changes to the terms and conditions of the existing awards. nine months ended October 30, 2016 : (in thousands, except for per unit amounts) Number of Units Recorded Liability Weighted Average Grant Date Fair Value (per unit) Aggregate Unrecognized Compensation Period Over Which Expected to be Recognized (in years) Balance at January 31, 2016 28 $ 3,870 $ 19.70 $ 221 0.4 Restricted stock units granted 25 23.40 Restricted stock units vested (30 ) 19.65 Restricted stock units forfeited — — Change in liability 502 Balance at October 30, 2016 23 $ 4,372 $ 23.67 $ 403 0.6 As of October 30, 2016 , the total number of vested but unsettled restricted stock units for non-employee directors is 173,657 units. As of October 30, 2016 , $4.4 million of the liability associated with these awards is included in “Other long-term liabilities” within the condensed consolidated balance sheets. Restricted Stock Units, Stock Settled, Non-Employee Directors . As a result of the June 2015 changes to the Company’s director compensation program, beginning in July 2015, the Company began granting new restricted stock units to non-employee directors which are expected to be settled with stock at the time of vesting. The grant date for these awards is equal to the measurement date. These awards are valued as of the measurement date and recognized as an expense over the requisite vesting period (typically one year). The following table summarizes the non-employee directors’ activity for restricted stock units settled with stock for the nine months ended October 30, 2016 : (in thousands, except for per unit amounts) Number of Units Weighted Average Grant Date Fair Value (per unit) Aggregate Intrinsic Value (1) Aggregate Unrecognized Compensation Period Over Which Expected to be Recognized (in years) Balance at January 31, 2016 24 $ 19.70 $ 186 0.4 Restricted stock units granted 21 23.40 Restricted stock units vested (25 ) 24.16 $ 616 Restricted stock units forfeited — — Balance at October 30, 2016 20 $ 23.67 $ 312 0.6 (1) Reflects the value of Semtech Corporation stock on the date that the restricted stock unit vested. Modification of Awards On December 19, 2014 and August 17, 2015, the Company modified the equity awards of certain executive officers by providing for the acceleration of vesting upon termination of their employment in certain circumstances in connection with a change in control of the Company. These modifications impacted the stock awards of 12 executive employees and resulted in no incremental compensation cost for the fiscal year ended January 31, 2016 or the three or nine month periods ended October 30, 2016 and October 25, 2015 . Warrant. On October 5, 2016 the Company issued a warrant (the “Warrant”) to Comcast Cable Communications Management LLC (“Comcast”) to purchase up to 1,086,957 shares (the “Warrant Shares”) of the Company’s common stock, par value $0.01 per share, representing a total of $30.0 million worth of common stock based on the average closing price over the 10 -trading day period ending October 4, 2016, at an exercise price of $ 0.01 per Warrant Share. The Warrant provides for net share settlement that, if elected by Comcast, will reduce the number of Warrant Shares issued upon exercise to reflect net settlement of the exercise price. Comcast may also request cash settlement of the Warrant upon exercise in lieu of the issuance of Warrant Shares; however, such cash settlement is at the sole and absolute discretion of the Company. The Warrant vested 10% on its issuance, and the remainder vests based on the achievement during the subsequent 30 -month period (“Milestone Period”) by Comcast (or its designee) of certain milestones related to the deployment of a LoRaWAN™-based network in cities around the country. The number of Warrant Shares are subject to customary adjustment provisions for stock split, reclassification, reorganization, consolidation, merger, and similar transactions. The Warrant has a term of seven years from October 5, 2016. The Warrant was issued by the Company to Comcast in connection with an agreement between the parties regarding the intended trial deployment by Comcast of a low-power wide-area Network (LPWAN) in the United States, based on the Company’s LoRa® Wireless Radio Frequency Technology. The Warrant is accounted for as equity. The cost of the Warrant is recognized as an offset to net sales over the respective performance period. The Warrant consists of five performance tranches. The cost associated with each tranche is recognized based on the fair value at each reporting date until vesting which is the measurement date. The following table summarizes the underlying Warrant Shares issued to Comcast for the nine months ended October 30, 2016 : (in thousands, except for per Warrant Share amounts) Number of Warrant Shares Weighted Average Grant Date Fair Value (per Warrant Share) Aggregate Intrinsic Value (1) Aggregate Unrecognized Expense Balance at January 31, 2016 — $ — — $ — Warrant shares granted 1,087 27.74 Warrant shares vested (109 ) 27.74 $ 3,015 Change in value — — 23,674 Balance at October 30, 2016 978 $ 27.74 $ 23,674 (1) Reflects the value of Semtech Corporation Warrant Shares on the date the Warrant Shares vested. Given the nominal exercise price of the Warrant Shares, the Company valued the awards using the closing price of the Company’s stock on the measurement date for shares that have vested and the fair value on the condensed consolidated balance sheets date for the other shares. As of October 30, 2016 , no part of the Warrant has been exercised, and the Warrant has an estimated life of seven years .

Investments

Investments	9 Months Ended
	Oct. 30, 2016
Investments [Abstract]
Investments	Investments Investments that have original maturities of three months or less are accounted for as cash equivalents. This includes money market funds, time deposits and United States (“U.S.”) government obligations. Temporary and long-term investments consist of government, bank and corporate obligations, with original maturity dates in excess of three months. Temporary investments have original maturities in excess of three months, but mature within twelve months of the balance sheet date. Long-term investments have original maturities in excess of twelve months. The Company determines the cost of securities sold based on the specific identification method. Realized gains or losses are reported in “Non-operating expense, net” within the unaudited condensed consolidated statements of income. The Company classifies its investments as “available-for-sale” because it may sell some securities prior to maturity. The Company’s investments are subject to market risk, primarily interest rate and credit risks. The Company’s investments are managed by a limited number of outside professional managers that operate within investment guidelines set by the Company. These guidelines include specified permissible investments, minimum credit quality ratings and maximum average duration restrictions and are intended to limit market risk by restricting the Company’s investments to high quality debt instruments with relatively short-term maturities. As of October 30, 2016 , the Company did not have any long-term investments. The following table summarizes the Company’s available-for-sale investments: October 30, 2016 January 31, 2016 (in thousands) Market Value Adjusted Cost Gross Unrealized Gain Market Value Adjusted Cost Gross Unrealized Gain Cash equivalents $ 16,908 $ 16,908 $ — $ 16,866 $ 16,866 $ — Total investments $ 16,908 $ 16,908 $ — $ 16,866 $ 16,866 $ — The following table summarizes the maturities of the Company’s available-for-sale investments: October 30, 2016 January 31, 2016 (in thousands) Market Value Adjusted Cost Market Value Adjusted Cost Within 1 year $ 16,908 $ 16,908 $ 16,866 $ 16,866 After 1 year through 5 years — — — — Total investments $ 16,908 $ 16,908 $ 16,866 $ 16,866 Unrealized gains and losses are the result of fluctuations in the market value of the Company’s available-for-sale investments and are included in “Accumulated other comprehensive income” within the condensed consolidated balance sheets. The following table summarizes net unrealized losses arising in the periods presented in addition to the tax associated with these comprehensive income items: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Unrealized gain (loss), net of tax $ — $ 129 $ (85 ) $ 266 Increase to deferred tax liability — 74 — 172 The Company did not generate any significant interest income in the three or nine month periods ended October 30, 2016 and October 25, 2015 . Equity and Cost Method Investments The Company accounts for its equity investments under the cost method of accounting when it does not have the ability to exercise significant influence over the investees. For investments where the Company has the ability to exercise significant influence, it uses the equity method of accounting. The Company’s total equity and cost method investments were $22.2 million and $20.2 million as of October 30, 2016 and January 31, 2016 . All of these investments are in private companies and are included in “Other assets” within the condensed consolidated balance sheets. The Company has the following investments which are accounted for as cost method investments: Entity Name Investment Value (in thousands) October 30, 2016 January 31, 2016 MultiPhy Ltd. $ 14,000 $ 12,000 Skorpios Technologies Inc. 3,000 3,000 Guangdong Dapu Telecom Technology Co., Ltd. 3,300 3,300 Senet, Inc. 1,900 1,900 Jariet Technologies Inc. — — Total $ 22,200 $ 20,200 The Company evaluated its cost method investments for indicators of impairment at October 30, 2016 . The Company did not identify any events or changes in circumstances that may have a significant adverse effect on the fair value of the investments and as a result did not estimate the fair value of its investments. On January 11, 2016, the Company announced that it had entered into a strategic agreement to accelerate the introduction of a 100Gbps single wavelength optical module solution. As part of this agreement, the Company made an investment under which the Company acquired preferred stock and a call option that is exercisable through June 30, 2018, that would allow the Company to purchase all of the outstanding equity of MultiPhy Ltd. (“MultiPhy”) at a fixed price. The Company does not expect to exercise this option within the next twelve months.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Oct. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Instruments Measured at Fair Value on a Recurring Basis Financial assets and liabilities measured and recorded at fair value on a recurring basis were presented within the Company’s condensed consolidated balance sheets as follows: Fair Value as of October 30, 2016 Fair Value as of January 31, 2016 (in thousands) Total (Level 1) (Level 2) (Level 3) Total (Level 1) (Level 2) (Level 3) Financial assets: Cash equivalents $ 16,908 $ 16,908 $ — $ — $ 16,866 $ 16,866 $ — $ — Derivative financial instruments 215 — 215 — — — — — Total financial assets $ 17,123 $ 16,908 $ 215 $ — $ 16,866 $ 16,866 $ — $ — Financial liabilities: Triune Earn-out $ — $ — $ — $ — $ — $ — $ — $ — Cycleo Earn-out 1,295 — — 1,295 1,457 — — 1,457 Derivative financial instruments 445 — 445 — — — — — Total financial liabilities $ 1,740 $ — $ 445 $ 1,295 $ 1,457 $ — $ — $ 1,457 During the nine months ended October 30, 2016 , the Company had no transfers of financial assets or liabilities between Level 1, Level 2 or Level 3. As of October 30, 2016 and January 31, 2016 , the Company had not elected the fair value option for any financial assets and liabilities for which such an election would have been permitted. The Company’s available-for-sale securities consist primarily of money market accounts that do not have a stated maturity date. The fair values of the foreign exchange forward contracts are valued using Level 2 inputs. Foreign currency forward contracts are valued using readily available foreign currency forward and interest rate curves. The fair value of each contract is determined by comparing the contract rate to the forward rate and discounting to the present value. Contracts in a gain position are recorded in the condensed consolidated balance sheets under the caption “Other current assets” and the value of contracts in a loss position are recorded under the caption “Accrued liabilities” within the condensed consolidated balance sheets. Please see Note 19 for further discussion of the Company’s derivative instruments. The Triune Earn-out liability is valued utilizing estimates of annual revenue and operating income (Level 3 inputs) during a period of approximately two -years ending January 2018. These estimates represent inputs for which market data are not available and are developed using the best information available about the assumptions that market participants would use when pricing the liability. The Cycleo Earn-out liability (see “Earn-out Liability” in Note 12) is valued utilizing estimates of annual revenue and operating income (Level 3 inputs) during a four -year period ending April 2020. These estimates represent inputs for which market data are not available and are developed using the best information available about the assumptions that market participants would use when pricing the liability. The Company measures contingent earn-out liabilities at fair value on a recurring basis using significant unobservable inputs classified within Level 3 of the fair value hierarchy. The Company uses a Monte Carlo valuation method as a valuation technique to determine the value of the earn-out liability. The significant unobservable inputs used in the fair value measurements are revenue projections over the earn-out period, and the probability outcome percentages assigned to each scenario. Significant increases or decreases to either of these inputs in isolation would result in a significantly higher or lower liability, with a higher liability capped by the contractual maximum of the contingent earn-out obligation. Ultimately, the liability will be equivalent to the amount paid, and the difference between the fair value estimate and amount paid will be recorded in earnings. For both the Triune Earn-out and Cycleo Earn-out, these companies have business profiles comparable to a start-up company. Accordingly, their respective revenue projections are subject to significant revisions. This characteristic has resulted in volatile changes to the measurement of fair value of the Triune Earn-out since the time of the Triune acquisition. The Company reviews and re-assesses the estimated fair value of contingent consideration on a quarterly basis, and the updated fair value could differ materially from the previous estimates. Changes in the estimated fair value of the Company’s contingent earn-out liabilities related to the time component of the present value calculation are reported in “Interest expense” within the unaudited condensed consolidated statements of income. Adjustments to the estimated fair value related to changes in all other unobservable inputs are reported in operating income. A reconciliation of the change in the earn-out liability during the nine months ended October 30, 2016 is as follows: (in thousands) Cycleo Triune Total Balance at January 31, 2016 $ 1,457 $ — $ 1,457 Changes in the fair value of contingent earn-out obligations (162 ) — (162 ) Balance as of October 30, 2016 $ 1,295 $ — $ 1,295 Instruments Not Recorded at Fair Value on a Recurring Basis Some of the Company’s financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate fair value due to their liquid or short-term nature. Such financial assets and financial liabilities include: cash and cash equivalents, net receivables, certain other assets, accounts payable, accrued expenses, accrued personnel costs, and other current liabilities. The Company’s long-term debt is not recorded at fair value on a recurring basis, but is measured at fair value for disclosure purposes. The fair value of the Company’s Term Loans (as defined in Note 10 ) is $67.8 million and $77.1 million and Revolving Commitments (as defined in Note 10 ) is $181.0 million as of both October 30, 2016 and January 31, 2016 , respectively. These are based on Level 2 inputs which are derived from transactions with similar amounts, maturities, credit ratings and payment terms. Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis The Company reduces the carrying amounts of its goodwill, intangible assets, long-lived assets and non-marketable equity securities to fair value when held for sale or determined to be impaired. For its investment in equity interests, the Company has not identified events or changes in circumstances that may have a significant adverse effect on the fair value of its equity investments during the first nine months of fiscal year 2017 .

Inventories

Inventories	9 Months Ended
	Oct. 30, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories, consisting of material, material overhead, labor, and manufacturing overhead, are stated at the lower of cost (first-in, first-out) or market and consist of the following: (in thousands) October 30, 2016 January 31, 2016 Raw materials $ 3,342 $ 2,094 Work in progress 40,731 40,940 Finished goods 18,606 20,841 Inventories $ 62,679 $ 63,875

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Oct. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill – Changes in the carrying amount of goodwill were as follows: (in thousands) Signal Integrity Power and High Reliability Wireless and Sensing Total Balance at January 31, 2016 $ 261,891 $ 49,384 $ 18,428 $ 329,703 Additions — — — — Balance at October 30, 2016 $ 261,891 $ 49,384 $ 18,428 $ 329,703 Goodwill is not amortized, but is tested for impairment using a two-step method on an annual basis and whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The recoverability of goodwill is measured at the reporting unit level by comparing the reporting unit’s carrying amount, including goodwill, to the fair market value of the reporting unit. Goodwill is allocated to three reporting units (Signal Integrity, Power and High Reliability and Wireless and Sensing) (see Note 14 ). The difference between the fair value and the carrying amount of these reporting units is one of several factors the Company will consider before reaching its conclusion about whether to perform the first step of the goodwill impairment test. Goodwill was tested for impairment as of November 30, 2015 , the date of the Company’s annual impairment review, at the reporting unit level for Signal Integrity, Power and High Reliability and Wireless and Sensing. The Company estimated the fair values using an income approach, as well as other generally accepted valuation methodologies. The cash flows for each reporting unit were based on discrete financial forecasts developed by management for planning purposes. Cash flows beyond the discrete forecasts were estimated using a terminal value calculation, which incorporated historical and forecasted financial trends for each identified reporting unit and considered perpetual earnings growth rates for publicly traded peer companies. Goodwill is measured at fair value on a non-recurring basis. That is, goodwill is not measured at fair value on an ongoing basis, but is subject to fair value adjustments using Level 3 inputs in certain circumstances (e.g., when there is evidence of impairment). At October 30, 2016 , the Company concluded that there were no indicators of such impairment. Purchased Intangibles – The following table sets forth the Company’s finite-lived intangible assets resulting from business acquisitions and technology licenses purchased, which continue to be amortized: October 30, 2016 January 31, 2016 (in thousands) Estimated Useful Life Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Core technologies 5-8 years $ 144,930 $ (87,753 ) $ 57,177 $ 148,210 $ (74,006 ) $ 74,204 Customer relationships 5-10 years 30,030 (19,147 ) 10,883 30,030 (15,847 ) 14,183 Technology licenses (1) 2 years 100 (96 ) 4 100 (57 ) 43 Other intangibles assets 1-5 years 6,600 (6,600 ) — 6,600 (6,600 ) — Total finite-lived intangible assets $ 181,660 $ (113,596 ) $ 68,064 $ 184,940 $ (96,510 ) $ 88,430 (1) Technology licenses relate to end-license agreements for intellectual property that is used by the Company in research and development activities and also has alternative future uses. Amortization expense related to technology licenses is reported as “Product development and engineering” within the unaudited condensed consolidated statements of income. For the three months ended October 30, 2016 and October 25, 2015 , amortization expense related to acquired finite-lived intangible assets was $6.3 million and $6.3 million , respectively. For the nine months ended October 30, 2016 and October 25, 2015 , amortization expense related to acquired finite-lived intangible assets was $19.0 million and $18.6 million , respectively. Amortization expense related to acquired finite-lived intangible assets is reported as “Intangible amortization” within the unaudited condensed consolidated statements of income. The estimated annual amount of future amortization expense for all finite-lived intangible assets will be as follows: (in thousands) To be recognized in: Core Technologies Customer Relationships Technology Licenses Total Remaining three months of fiscal year 2017 $ 5,188 $ 1,100 $ 4 $ 6,292 Fiscal year 2018 20,744 4,400 — 25,144 Fiscal year 2019 17,332 4,400 — 21,732 Fiscal year 2020 9,905 950 — 10,855 Fiscal year 2021 3,056 33 — 3,089 Thereafter 952 — — 952 Total expected amortization expense $ 57,177 $ 10,883 $ 4 $ 68,064 As of October 30, 2016 , the Company had no intangible assets classified as having an indefinite life.

Credit Facilities

Credit Facilities	9 Months Ended
	Oct. 30, 2016
Debt Instruments [Abstract]
Credit Facilities	Credit Facilities On May 2, 2013, Semtech Corporation, with each of its domestic subsidiaries as guarantors (the “Prior Guarantors”), entered into a credit agreement (the “Prior Credit Agreement”) with the lenders referred to therein (the “Prior Lenders”) and HSBC Bank USA, National Association, as administrative agent and as swing line lender and letter of credit issuer. In accordance with the Prior Credit Agreement, the Prior Lenders provided Semtech Corporation with senior secured first lien credit facilities in an aggregate principal amount of $400.0 million for a five year term, consisting of term loans in an aggregate initial principal amount of $150.0 million (the “Prior Term Loans”) and revolving credit commitments in an aggregate principal amount of $250.0 million (the “Prior Revolving Commitments”). The Prior Revolving Commitments contained sub-facilities that could be used as follows: up to $40.0 million for letters of credit, up to $25.0 million for Swing Line Loans (as defined below), and up to $40.0 million for revolving loans and letters of credit in certain currencies other than U.S. Dollars (“Alternative Currencies”). “Swing Line Loans” refer to Base Rate (as defined below) loans made in immediately available funds denominated in dollars by the swing line lender in its sole and absolute discretion. As of October 30, 2016 , there were no amounts outstanding under the letters of credit, Swing Line Loans, and Alternative Currencies. Interest on loans made under the Prior Credit Agreement in U.S. Dollars accrued, at Semtech’s option, at a rate per annum equal to (1) the Base Rate plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) London Interbank Offered Rate (“LIBOR”) (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio. The “Base Rate” is equal to a fluctuating rate equal to the highest of (a) the prime rate (as published by The Wall Street Journal), (b) ½ of 1% above the federal funds effective rate or (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1% . Interest on loans in Alternative Currencies, other than Canadian Dollars, accrued at a rate per annum equal to LIBOR (determined with respect to deposits in the applicable Alternative Currency) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio. Interest on loans in Canadian Dollars accrued at a rate per annum equal to the CDOR Rate (as defined below) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio. The “CDOR Rate” for any interest period is the rate equal to the sum of: (a) the rate determined by the administrative agent with reference to the arithmetic average of the discount rate quotations of all institutions listed for CAD Dollar-denominated bankers’ acceptances displayed and identified on the “Reuters Screen CDOR Page” and (b) 0.10% per annum. CDOR Commitment fees on the unused portion of the Prior Revolving Commitments accrued at a rate per annum ranging from 0.20% to 0.45% depending upon Semtech’s consolidated leverage ratio. Interest was payable monthly for a Base Rate loan and swing line loan and quarterly for a Euro dollar rate loan. As of October 30, 2016 , the interest rates payable on both the Prior Term Loans and the Prior Revolving Commitments was 2.28% . As of October 30, 2016 , there was $67.8 million outstanding under the Prior Term Loans and $181.0 million in revolving loans outstanding pursuant to the Prior Revolving Commitments. The Prior Term Loans and the Prior Revolving Commitments (and related revolving loans) were scheduled to mature on May 1, 2018 . All obligations of Semtech Corporation under the Prior Credit Agreement were unconditionally guaranteed by each of the Prior Guarantors and were secured by a first priority security interest in substantially all of the assets of Semtech Corporation and the Prior Guarantors, subject to certain customary exceptions. Semtech Corporation and the Prior Guarantors were subject to customary covenants under the Prior Credit Agreement, including the maintenance of a minimum interest ratio of 3.50 to 1.00 and a maximum total consolidated leverage ratio of 3.00 to 1.00. Semtech Corporation and the Prior Guarantors were in compliance with such financial covenants as of October 30, 2016 . The Prior Credit Agreement also contained customary provisions pertaining to events of default. If any event of default had occurred, the principal, interest, and any other monetary obligations on all the then outstanding amounts could have become due and payable immediately. On November 15, 2016, the Company, with each of its domestic subsidiaries as guarantors, entered into an amended and restated credit agreement (the “Amended and Restated Credit Agreement”) with the lenders referred to therein (the “Lenders”) and HSBC Bank USA, National Association, as administrative agent and as swing line lender and letter of credit issuer. The Amended and Restated Credit Agreement consists of a senior secured term A loan facility in the principal amount of $150.0 million and a senior secured revolving credit facility in the principal amount of $250.0 million , each of which is scheduled to mature in November 2021. The Amended and Restated Credit Agreement amended and restated the Prior Credit Agreement that was scheduled to mature in May of 2018 (see Note 20 for discussion regarding Subsequent Events).

Income Taxes

Income Taxes	9 Months Ended
	Oct. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s effective tax rate differs from the statutory federal income tax rate of 35% due primarily to regional mix of income, valuation allowances in the U.S., and certain undistributed foreign earnings for which no U.S. taxes are provided because such earnings are intended to be indefinitely reinvested outside of the U.S. The Company uses a two-step approach to recognize and measure uncertain tax positions (“UTP”). The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement. A reconciliation of the beginning and ending amount of net unrecognized tax benefits is as follows: (in thousands) Balance at January 31, 2016 $ 8,432 Additions based on tax positions related to the current year 80 Reductions for tax positions of prior years, net (121 ) Reductions for settlements with tax authorities — Balance as of October 30, 2016 $ 8,391 The gross unrecognized tax benefit (before federal impact of state items) was $10.6 million at both October 30, 2016 and January 31, 2016 . Included in the balance of unrecognized tax benefits at October 30, 2016 and January 31, 2016 , is $8.4 million and $8.4 million of net tax benefit (after federal impact of state items), respectively, that, if recognized, would impact the effective tax rate, subject to the valuation allowance. The liability for UTP is reflected within the condensed consolidated balance sheets as follows: (in thousands) October 30, 2016 January 31, 2016 Deferred tax assets - non-current $ 7,121 $ 7,162 Other long-term liabilities 1,270 1,270 Total accrued taxes $ 8,391 $ 8,432 The Company’s policy is to include net interest and penalties related to unrecognized tax benefits within the provision for taxes within the unaudited condensed consolidated statements of income. The Company had approximately $293,000 of net interest and penalties accrued at October 30, 2016 and January 31, 2016 . Tax years prior to 2012 (the Company’s fiscal year 2013) are generally not subject to examination by the U.S. Internal Revenue Service (“IRS”) except for items involving tax attributes that have been carried forward to tax years whose statute of limitations remains open. The Company is currently under IRS audit for fiscal years 2012 and 2013 and expects to close those audits within the next twelve months. The Company’s reserves for UTP’s are expected to be sufficient to address matters that may arise under examination. For state returns, the Company is generally not subject to income tax examinations for years prior to 2011 (the Company’s fiscal year 2012). The Company has a significant tax presence in Switzerland for which Swiss tax filings have been examined through fiscal year 2015. The Company is also subject to routine examinations by various foreign tax jurisdictions in which it operates.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Oct. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	Commitments and Contingencies In accordance with accounting standards regarding loss contingencies, the Company accrues an undiscounted liability for those contingencies where the incurrence of a loss is probable and the amount can be reasonably estimated. The Company also discloses the amount accrued and the amount of a reasonably possible loss in excess of the amount accrued, if such disclosure is necessary for its financial statements not to be misleading. The Company does not record liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated, or when the liability is believed to be only reasonably possible or remote. The Company evaluates at least quarterly, developments in its legal matters that could affect the amount of liability that has been previously accrued, and makes adjustments as appropriate. Significant judgment is required to determine both probability and the estimated amount. The Company may be unable to estimate a possible loss or range of possible loss due to various reasons, including, among others: (i) if the damages sought are indeterminate; (ii) if the proceedings are in early stages, (iii) if there is uncertainty as to the outcome of pending appeals, motions or settlements, (iv) if there are significant factual issues to be determined or resolved, and (v) if there are novel or unsettled legal theories presented. In such instances, there is considerable uncertainty regarding the ultimate resolution of such matters, including a possible eventual loss, if any. From time to time, the Company is involved in various claims, litigation, and other legal actions that are normal to the nature of its business, including with respect to intellectual property, contract, product liability, employment, and environmental matters. The Company’s evaluation of legal matters and proceedings often involves a series of complex assessments by management about future events and can rely heavily on estimates and assumptions. While the consequences of certain unresolved matters and proceedings are not presently determinable, and an estimate of the probable and reasonably possible loss or range of loss in excess of amounts accrued for such proceedings cannot be reasonably made, an adverse outcome from such proceedings could have a material adverse effect on the Company’s earnings in any given reporting period. However, in the opinion of management, after consulting with legal counsel, and taking into account insurance coverage, any ultimate liability related to current outstanding claims and lawsuits, individually or in the aggregate, is not expected to have a material adverse effect on the Company’s financial statements, as a whole. However, legal matters are inherently unpredictable and subject to significant uncertainties, some of which are beyond the Company’s control. As such, even though the Company intends to vigorously defend itself with respect to its legal matters, there can be no assurance that the final outcome of these matters will not materially and adversely affect the Company’s business, financial condition, results of operations, or cash flows. The Company’s currently pending legal matters of note are discussed below: Environmental Matters In 2001, the Company was notified by the California Department of Toxic Substances Control (“State”) that it may have liability associated with the clean-up of the one-third acre Davis Chemical Company site in Los Angeles, California. The Company has been included in the clean-up program because it was one of the companies that used the Davis Chemical Company site for waste recycling and/or disposal between 1949 and 1990. The Company joined with other potentially responsible parties that sent acetone to the site and entered into a Consent Order with the State that required the group to perform a soils investigation at the site and submit a remediation plan. The State has approved the remediation plan, which addressed the group’s initial obligations under the Consent Order. The Consent Order does not require the group to remediate the site and the State has indicated it intends to look to other parties for remediation. To date, the Company’s share of the group’s expenses has not been material and has been expensed as incurred. There is a pending settlement offer that would potentially resolve most, if not all, of the acetone group’s potential liability. More recently, the State has indicated that it will pursue a smaller group of parties for additional remediation and/or costs, in particular parties the State alleges provided chlorinated solvents for recycling, including the Company. Due to the fact that there are fewer parties that are alleged to have provided chlorinated solvent wastes, the potential share of this alleged liability is much larger than the Company’s share of acetone group potential liability. Settlement discussions regarding the potential liability for chlorinated solvents at the site have recently been initiated, but it is too soon to tell if those discussions will lead to a negotiated resolution of the issues. The Company has used an environmental firm, specializing in hydrogeology, to perform monitoring of the groundwater at the Company’s former facility in Newbury Park, California that was leased for approximately 40 years. The Company vacated the building in May 2002. Certain contaminants have been found in the local groundwater and site soils. The location of key soil contamination (and some related site groundwater impact associated with the soil contamination) is concentrated in and found to emanate from an area of an underground storage tank that the Company believes to have been installed and primarily used in the early 1960s by a former tenant at the site who preceded the Company’s tenancy. There are no litigation claims pending with respect to environmental matters at the Newbury Park site. The Los Angeles Regional Water Quality Control Board (“RWQCB”) having authority over the site issued joint instructions in November 2008, ordering the Company and the current owner of the site to perform additional assessments and surveys, and to create ongoing groundwater monitoring plans before any final regulatory action for “no further action” may be approved. In September 2009, the regulatory agency issued supplemental instructions to the Company and the current site owner regarding previously ordered site assessments, surveys and groundwater monitoring. In October 2013, an order was issued including a scope of proposed additional site work, monitoring, and proposed remediation activities. The Company filed appeals of the October 2013 order seeking reconsideration by the RWQCB and review by the State Water Resources Control Board (“SWRCB”) of the removal of two other potentially responsible parties, and seeking clarification of certain other factual findings. In April 2015, the RWQCB denied the Company’s request to name the two other potentially responsible parties to the order, but did correct certain findings of fact identified by the Company in its petition for reconsideration. The SWRCB has not yet ruled on the Company’s petition for review of the RWQCB’s action as the petition was filed with a request it be held in abeyance. The Company has been engaged with the regulatory agency, including technical discussion between the Company’s environmental firm and RWQCB staff, and has initiated the technical efforts to comply with the order. The Company submitted technical reports prepared by the environmental firm to the RWQCB and has received confirmation regarding the satisfaction of portions of the order. The Company also submitted a remedial action plan prepared by the environmental firm outlining the cleanup of soil, groundwater, and soil vapor at the site. The Company's contractors have installed new monitoring wells and have submitted plans and applications in order to initiate pilot testing of a soil vapor extraction system. The parties are continuing to work toward compliance with the October 2013 order and anticipate working cooperatively on any ultimate proposed cleanup and abatement work. The Company has accrued liabilities where it is probable that a loss will be incurred and the cost or amount of loss can be reasonably estimated. Based on the latest determinations by the RWQCB and the draft remedial action plan, the Company determined a revised range of probable loss between $5.2 million and $7.5 million . Given the uncertainties associated with environmental assessment and the remediation activities, the Company is unable to determine a best estimate within the range of loss. Therefore, the Company has recorded the minimum amount of probable loss as follows within the Company’s condensed consolidated balance sheets. (in thousands) Accrued Liability Other-Long Term Liability Total Balance at January 31, 2016 $ 1,150 $ 4,180 $ 5,330 Change in estimate (499 ) 499 — Utilization (116 ) — (116 ) Balance at October 30, 2016 $ 535 $ 4,679 $ 5,214 These estimates could change as a result of changes in planned remedial actions, further actions from the regulatory agency, remediation technology, and other factors. Indemnification Product Warranties The Company’s general warranty policy provides for repair or replacement of defective parts. In some cases, a refund of the purchase price is offered. In certain instances the Company has agreed to other or additional warranty terms, including indemnification provisions. The product warranty accrual reflects the Company’s best estimate of probable liability under its product warranties. The Company accrues for known warranty issues if a loss is probable and can be reasonably estimated, and accrues for estimated incurred but unidentified issues based on historical experience. Historically, warranty expense has been immaterial to the Company’s consolidated financial statements. Earn-out Liability Pursuant to the terms of the amended earn-out arrangement (“Cycleo Amended Earn-out”) with the former stockholders of Cycleo SAS (“Cycleo Earn-out Beneficiaries”), which the Company acquired on March 7, 2012, the Company potentially may make payments totaling up to approximately $16.0 million based on the achievement of a combination of certain revenue and operating income milestones over a defined period (“Cycleo Defined Earn-out Period”). The Cycleo Defined Earn-out Period covers the period April 27, 2015 to April 26, 2020. For certain of the Cycleo Earn-out Beneficiaries, payment of the earn-out liability is contingent upon continued employment and is accounted for as post-acquisition compensation expense over the service period. The portion of the earn-out liability that is not dependent on continued employment is not considered as compensation expense. The Company recorded a liability for the Cycleo Amended Earn-out of $8.3 million and $6.3 million as of October 30, 2016 and January 31, 2016 , respectively, of which $1.8 million is expected to be paid within twelve months. Pursuant to the terms of the Triune Earn-out with the former members of Triune (“Triune Earn-out Beneficiaries”), which the Company acquired on March 4, 2015, the Company potentially may make payments totaling up to approximately $70.0 million based on achievement of certain net revenue targets measured at each fiscal year end, starting with fiscal year 2016 and ending in fiscal year 2018. An additional payment of up to $16.0 million may be made based upon a combination of cumulative revenue and contribution margin targets measured from the acquisition date through the end of the Company’s fiscal year 2018. For certain of the Triune Earn-out Beneficiaries, payment of the earn-out liability is contingent upon continued employment and is accounted for as post-acquisition compensation expense over the service period. The portion of the earn-out liability that is not dependent on continued employment is not considered as compensation expense. The Triune Earn-out targets for fiscal year 2016 were not met and the Company does not expect the fiscal year 2017 or 2018 targets to be achieved. Refer to Note 7 for additional discussion regarding fair value measurements. A summary of earn-out liabilities by classification follows: Balance at October 30, 2016 Balance at January 31, 2016 (in thousands) Cycleo Triune Total Cycleo Triune Total Compensation expense $ 6,379 $ — $ 6,379 $ 4,397 $ — $ 4,397 Not conditional upon continued employment 1,295 — 1,295 1,457 — 1,457 Interest expense 590 — 590 405 — 405 Total liability $ 8,264 $ — $ 8,264 $ 6,259 $ — $ 6,259 Amount expected to be settled within twelve months $ 1,829 $ — $ 1,829 $ 2,155 $ — $ 2,155

Concentration of Risk

Concentration of Risk	9 Months Ended
	Oct. 30, 2016
Risks and Uncertainties [Abstract]
Concentration of Risk	Concentration of Risk The following significant customers accounted for at least 10% of net sales in one or more of the periods indicated: Three Months Ended Nine Months Ended (percentage of net sales) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Arrow (and affiliates) 11 % 10 % 9 % 9 % The Company did not have any customer that accounted for at least 10% of total net receivables as of October 30, 2016 or January 31, 2016 . Outside Subcontractors and Suppliers The Company relies on a limited number of outside subcontractors and suppliers for the production of silicon wafers, packaging and certain other tasks. Disruption or termination of supply sources or subcontractors, including due to natural disasters such as an earthquake or other causes, could delay shipments and could have a material adverse effect on the Company. Although there are generally alternate sources for these materials and services, qualification of the alternate sources could cause delays sufficient to have a material adverse effect on the Company. Several of the Company’s outside subcontractors and suppliers, including third-party foundries that supply silicon wafers, are located in foreign countries, including China, Taiwan, Europe and Israel. The Company’s largest source of silicon wafers is an outside foundry located in China and a significant amount of the Company’s assembly and test operations are conducted by third-party contractors in China, Malaysia, Taiwan, Thailand, Korea and the Philippines. For the third quarter of fiscal years 2017 and 2016 , respectively, approximately 24% and 29% , respectively, of the Company’s silicon in terms of cost of wafers was supplied by a third-party foundry in China, and these percentages could be higher in future periods. In the third quarter of fiscal year 2017 , authorized distributors accounted for approximately 64% of the Company’s net sales compared to approximately 56% in the third quarter of fiscal year 2016 . Generally, the Company does not have long-term contracts with its distributors and most can terminate th eir agreement with little or no notice. For the third quarter of fiscal year 2017 , our two largest distributors were based in Asia.

Segment Information

Segment Information	9 Months Ended
	Oct. 30, 2016
Segment Reporting [Abstract]
Segment Information	Segment information Segment Information The Company had five operating segments that existed prior to the third quarter of fiscal year 2017 and currently has four . The Company’s CEO functions as the CODM. The Company’s CODM makes operating decisions and assesses performance based on these operating segments. The four operating segments: Protection Products Group, Power and High Reliability Products Group, Signal Integrity Products Group, and Wireless and Sensing Products Group, all have similar economic characteristics and have been aggregated into one reportable segment identified in the table below as the “Semiconductor Products Group”. On August 5, 2016, the Company completed its divestiture of its Snowbush IP business. Beginning in the third quarter of fiscal year 2017, the Company no longer has a Systems Innovation Group or an “All others” category, which used to be a separate operating segment. The Company’s assets are commingled among the various reporting units and the CODM does not use that information in making operating decisions or assessing performance. Therefore, the Company has not included asset information by segment below. Net sales by segment are as follows: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Semiconductor Products Group $ 137,185 $ 115,795 $ 404,036 $ 369,690 All others — 15 205 1,920 Total $ 137,185 $ 115,810 $ 404,241 $ 371,610 Income by segment and reconciliation to consolidated operating income: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Semiconductor Products Group $ 33,013 $ 22,019 $ 92,973 $ 70,054 All others 25,214 (1,818 ) 22,738 (6,375 ) Operating Income by segment 58,227 20,201 115,711 63,679 Items to reconcile segment operating income to consolidated income before taxes Intangible amortization and impairments 6,286 6,308 19,017 18,648 Share-based compensation 9,395 5,117 21,199 13,397 Changes in the fair value of contingent earn-out obligations — (14,186 ) (162 ) (13,618 ) Restructuring charges — 962 — 4,526 Environmental reserve — — — 2,855 Other non-segment related (income) expenses 3,139 2,792 5,938 10,073 Amortization of fair value adjustments related to acquired PP&E 308 310 925 948 Interest expense, net 1,890 1,964 5,857 5,698 Non-operating expense, net 690 777 871 1,152 Income before taxes $ 36,519 $ 16,157 $ 62,066 $ 20,000 Information by Product Line The Company operates exclusively in the semiconductor industry and primarily within the analog and mixed-signal sector. The table below provides net sales activity by product line on a comparative basis for all periods. Three Months Ended Nine Months Ended (in thousands, except percentages) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Signal Integrity $ 60,550 44 % $ 52,449 45 % $ 193,745 48 % $ 165,780 44 % Protection 40,250 29 % 33,225 29 % 108,296 27 % 105,339 28 % Wireless and Sensing 24,070 18 % 16,567 14 % 60,514 15 % 54,898 15 % Power and High-Reliability 15,984 12 % 13,554 12 % 45,150 11 % 43,673 12 % Systems Innovation — — % 15 — % 205 — % 1,920 1 % Other: Warrant Shares (3,669 ) (3 )% — — % (3,669 ) (1 )% — — % Total net sales $ 137,185 100 % $ 115,810 100 % $ 404,241 100 % $ 371,610 100 % The cost of the Warrant granted is recognized as an offset to net sales over the respective performance period (see Note 5 for discussion regarding Share-Based Compensation). Geographic Information The Company generates virtually all of its sales from its Semiconductor Products Group through sales of analog and mixed-signal devices. Net sales activity by geographic region is as follows: Three Months Ended Nine Months Ended October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Asia-Pacific 80 % 70 % 79 % 72 % North America 16 % 20 % 16 % 18 % Europe 7 % 10 % 8 % 10 % Other: Warrant Shares (3 )% — % (3 )% — % 100 % 100 % 100 % 100 % The Company attributes sales to a country based on the ship-to address. The table below summarizes sales activity to countries that represented greater than 10% of total net sales for one or more of the periods presented: Three Months Ended Nine Months Ended (percentage of total sales) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 China (including Hong Kong) 46 % 45 % 45 % 44 % United States 11 % 14 % 11 % 12 % Other: Warrant Shares (3 )% — % (3 )% — % The Company’s regional income (loss) from continuing operations before income taxes is as follows: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Domestic $ 937 $ 21,146 $ (13,048 ) $ 3,785 Canada 31,385 2,440 49,302 16,494 United Kingdom 3,568 4,984 14,150 17,328 Switzerland 764 (13,411 ) 7,791 (5,063 ) Japan 344 1,424 2,470 2,486 Other Foreign (479 ) (426 ) 1,401 (15,030 ) Total $ 36,519 $ 16,157 $ 62,066 $ 20,000 Additionally, the impact of the Warrant is included in the domestic performance above.

Stock Repurchase Program

Stock Repurchase Program	9 Months Ended
	Oct. 30, 2016
Equity [Abstract]
Stock Repurchase Program	Stock Repurchase Program Stock Repurchase Program The Company maintains a stock repurchase program that was initially approved by its Board of Directors in March 2008. The stock repurchase program does not have an expiration date and the Company’s Board of Directors has authorized expansion of the program over the years. The following table summarizes activity under the repurchase program for the three and nine month periods listed below: Three Months Ended Nine Months Ended October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 (in thousands, except number of shares) Shares Value Shares Value Shares Value Shares Value Repurchase Program expenditures — $ — 491,316 $ 7,464 23,968 $ 538 2,681,476 $ 57,311 As of October 30, 2016 , the Company had repurchased $136.2 million in shares of its common stock under the program since inception and the current remaining authorization under the program is $62.2 million . Under the program, the Company may repurchase its common stock at any time or from time to time, without prior notice, subject to market conditions and other considerations. The Company’s repurchases may be made through Rule 10b5-1 or other trading plans, open market purchases, privately negotiated transactions, block purchases or other transactions. The Company intends to fund repurchases under the program from cash on hand. The Company has no obligation to repurchase any shares under the program and may suspend or discontinue it at any time.

Divestitures

Divestitures	9 Months Ended
	Oct. 30, 2016
Discontinued Operations and Disposal Groups [Abstract]
Divestiture	Divestitures In the first quarter of fiscal year 2016, the Company completed its divestiture of its defense and microwave communications infrastructure business to Jariet Technologies, Inc. (“Jariet”) in exchange for an equity interest in that company. For the three months ended October 25, 2015 , the defense and microwave communications infrastructure business accounted for $0.2 million in net revenue and non-recurring engineering (“NRE”) reimbursements. For the nine months ended October 25, 2015 , the defense and microwave communications infrastructure business accounted for $4.3 million in net revenue and NRE reimbursements. This business was part of the Sierra Monolithics, Inc. acquisition completed by the Company in December 2009. Under the terms of the transaction with Jariet, the Company contributed assets, including inventory and equipment with a net book value of $0.6 million in exchange for an equity interest in the form of preferred stock , representing an approximately 21% voting interest in Jariet. Due to the anticipated continuing cash flows from its investment in Jariet, the Company did not account for the divestiture as a discontinued operation. In addition to the contribution of assets, certain contracts were novated with future performance responsibilities being transferred to Jariet. The investment in Jariet was written off in the third quarter of fiscal year 2016. On August 5, 2016, the Company completed its divestiture of its Snowbush IP business (previously part of the Company’s Systems Innovation Group) to Rambus for a purchase price of $32.0 million in cash along with the opportunity to receive additional payments from Rambus through 2022 based upon a percentage of sales by Rambus of new products expected to be developed by Rambus from the disposed assets. The Company recognized a gain of $25.0 million on the disposition of this business in the third quarter of fiscal year 2017, which is recorded in “Gain on disposition of business operations” within the condensed consolidated statements of income. The Company is accounting for any potential receipt of proceeds a gain contingency; therefore, any additional payments will be recognized as they are received. The cash proceeds from the disposition of this business are included in “Proceeds from disposition of business operations” within the cash flows from investing activities section of the unaudited condensed consolidated statements of cash flows.

Restructuring

Restructuring	9 Months Ended
	Oct. 30, 2016
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities Disclosure	Restructuring During fiscal year 2016, Semtech Corporation announced a worldwide reduction in force as part of an overall plan to align operating expenses with business conditions and to leverage recent infrastructure investments. Restructuring related liabilities are included within “Accrued liabilities” within the condensed consolidated balance sheets as of October 30, 2016 and January 31, 2016 , respectively. Restructuring charges, if any, are presented within “Restructuring charge” within the unaudited condensed consolidated statements of income. The following table summarizes the restructuring activity for the nine months ended October 30, 2016 : (in thousands) One-time employee termination benefits Balance at January 31, 2016 $ 342 Adjustments — Cash payments (336 ) Balance at October 30, 2016 $ 6

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Oct. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities The Company analyzes its investments or other interests to determine whether it represents a variable interest in a variable interest entity (“VIE”). If so, the Company evaluates the facts to determine whether it is the primary beneficiary. The Company considers itself to be the primary beneficiary when it has both the power to direct activities of the VIE that most significantly impact the VIEs economic performance and the obligation to absorb losses from or the right to receive benefits of the VIE that could potentially be significant to the VIE. With regards to its investment in MultiPhy, the Company concluded that its equity interest represents a variable interest, but it is not the primary beneficiary as prescribed in ASC 810. Specifically, in reaching this conclusion, the Company considered the activities that most significantly drive profitability for MultiPhy and determined that the activity that most significantly drove profitability was related to the technology and related product road maps. The Company has a board observer role and thus concluded that it was not in a position of decision-making or other authority to influence MultiPhy’s activities that could be considered significant with respect to its operations, including research and development plans and changes to the product road map. As of October 30, 2016 , the Company’s maximum exposure to loss as a result of its investment in MultiPhy is limited to the $14.0 million investment as described further in Note 6 . As part of its investment in MultiPhy, the Company received a call option that would allow the Company to purchase all of the outstanding equity interests of MultiPhy. The call option, which is currently out of the money, is exercisable through June 30, 2018.

Derivatives and Hedging Activit

Derivatives and Hedging Activities	9 Months Ended
	Oct. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivatives and Hedging Activities The Company is exposed to certain risk arising from both its business operations and economic conditions and principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company, on a routine basis and in the normal course of business, experiences expenses denominated in Swiss Franc (“CHF”), Canadian Dollar (“CAD”) and Great British Pound (“GBP”). Such expenses expose the Company to exchange rate fluctuations between these foreign currencies and the U.S. Dollar (“USD”). The Company uses derivative financial instruments in the form of forward contracts, to mitigate risk associated with adverse movements in these foreign currency exchange rates on a portion of foreign denominated expenses expected to be realized during the current and following fiscal year. Currency forward contracts involve fixing the exchange rate for delivery of a specified amount of foreign currency on a specified date. The Company records all derivatives within the condensed consolidated balance sheets at fair value, with assets included in “Other current assets” and liabilities included in “Accrued liabilities”. The Company’s accounting treatment for these instruments is based on whether or not the instruments are designated as a hedging instrument. The Company is currently applying hedge accounting to all foreign currency derivatives and has designated these hedges as cash flow hedges. At October 30, 2016 , the Company had the following outstanding foreign exchange contracts: (in thousands) Foreign Exchange Contracts Number of Instruments Buy Notional Value Sell Notional Value Sell USD/Buy CHF Forward Contract 3 Fr. 2,672 $ 2,732 Sell USD/Buy CAD Forward Contract 3 C$ 6,337 $ 4,532 Sell USD/Buy GBP Forward Contract 15 £ 10,744 $ 13,568 Total 21 These contracts, with maturities extending into the subsequent fiscal year, met the criteria for cash flow hedges and the unrealized gains or losses, after tax, are recorded as a component of accumulated other comprehensive gain in shareholders’ equity. The effective portions of cash flow hedges are recorded in accumulated other comprehensive income (“AOCI”) until the hedged item is recognized in selling, general and administrative (“SG&A”) expense within the unaudited condensed consolidated statements of income when the underlying hedged expense is recognized. Any ineffective portions of cash flow hedges are recorded in “Non-operating (expense) income, net” within the Company’s unaudited condensed consolidated statements of income. The Company presents its derivative assets and liabilities at their gross fair values on the condensed consolidated balance sheets. The table below summarizes the carrying values of derivative instruments as of October 30, 2016 and January 31, 2016 : Carrying Values of Derivative Instruments as of October 30, 2016 (in thousands) Fair Value - Assets (2) Fair Value - (Liabilities) (2) Derivative Net Carrying Value Derivatives designated as hedging instruments Foreign exchange contracts (1) $ 215 $ (445 ) $ (230 ) Total derivatives $ 215 $ (445 ) $ (230 ) Carrying Values of Derivative Instruments as of January 31, 2016 Fair Value - Assets (2) Fair Value - (Liabilities) (2) Derivative Net Carrying Value Derivatives designated as hedging instruments Foreign exchange contracts (1) $ — $ — $ — Total derivatives $ — $ — $ — (1) Assets are included in “Other current assets” and liabilities are included in “Accrued liabilities” within the condensed consolidated balance sheets. (2) The fair values of the foreign exchange forward contracts are valued using Level 2 inputs. Please refer to Note 7 . The following table summarizes the amount of income recognized from derivative instruments for the three months ended October 30, 2016 and October 25, 2015 as well as the line items within the accompanying unaudited condensed consolidated statements of income where the results are recorded for cash flow hedges: Amount of Gain (Loss) Recognized in AOCI on Derivative (Effective Portion) Location of Gain or Loss into Income (Effective Portion) Amount of (Gain) Loss Reclassified from AOCI into Income (Effective Portion) Location of Gain or Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Three Months Ended Three Months Ended Three Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Sell USD/Buy CHF Forward Contract $ (85 ) $ — SG&A $ (24 ) $ — SG&A $ (1 ) $ — Sell USD/Buy CAD Forward Contract (141 ) — SG&A (334 ) — SG&A — — Sell USD/Buy GBP Forward Contract (196 ) — SG&A 270 — SG&A (2 ) — $ (422 ) $ — $ (88 ) $ — $ (3 ) $ — The following table summarizes the amount of income recognized from derivative instruments for the nine months ended October 30, 2016 and October 25, 2015 as well as the line items within the accompanying unaudited condensed consolidated statements of income where the results are recorded for cash flow hedges: Amount of Gain (Loss) Recognized in AOCI on Derivative (Effective Portion) Location of Gain or Loss into Income (Effective Portion) Amount of (Gain) Loss Reclassified from AOCI into Income (Effective Portion) Location of Gain or Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Nine Months Ended Nine Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Sell USD/Buy CHF Forward Contract $ 51 $ — SG&A $ (72 ) $ — SG&A $ — $ — Sell USD/Buy CAD Forward Contract 1,113 — SG&A (909 ) — SG&A 5 — Sell USD/Buy GBP Forward Contract (843 ) — SG&A 435 — SG&A (3 ) — $ 321 $ — $ (546 ) $ — $ 2 $ — The amount of losses, net of tax, related to the effective portion of derivative instruments designated as cash flow hedges included in “Accumulated other comprehensive income” within the condensed consolidated balance sheets as of October 30, 2016 and October 25, 2015 was $0.2 million and $0.0 million . Any gains or losses under these contracts are expected to be realized and reclassified to selling, general and administrative within the next fifteen months.

Subsequent Events

Subsequent Events	9 Months Ended
	Oct. 30, 2016
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On November 15, 2016 (the “Closing Date”), the Company, with certain of its domestic subsidiaries as guarantors (the “Guarantors”), entered into the Amended and Restated Credit Agreement with the Lenders, and HSBC Bank USA, National Association, as administrative agent and as swing line lender and letter of credit issuer. The Amended and Restated Credit Agreement amended and restated the Prior Credit Agreement. Pursuant to the Amended and Restated Credit Agreement, the Lenders provided the Company with senior secured first lien credit facilities in an aggregate principal amount of $400.0 million , consisting of term loans in an aggregate initial principal amount of $150.0 million and revolving commitments in an aggregate principal amount of $250.0 million . Up to $40.0 million of the revolving commitments may be used to obtain letters of credit, up to $25.0 million of the revolving commitments may be used to obtain swing line loans, and up to $40.0 million of the revolving commitments may be used to obtain revolving loans and letters of credit in certain currencies other than U.S. Dollars. Each of the term loans and the revolving commitments is scheduled to mature on November 12, 2021 . As of November 15, 2016, there were no amounts outstanding under the letters of credit, swing line loans and alternative currency sub-facilities. As of November 15, 2016, $247.0 million of borrowings were outstanding under the Amended and Restated Credit Agreement, consisting of $150.0 million in term loans and $97.0 million in revolving loans, and there was $153.0 million of undrawn revolving commitments. The proceeds of the revolving credit facility may be used by the Company for capital expenditures, permitted acquisitions, permitted dividends, working capital and general corporate purposes. The Amended and Restated Credit Agreement provides that, subject to certain conditions, the Company may request the establishment of one or more additional term loan facilities and/or increases to the revolving commitments in an aggregate principal amount not to exceed the sum of (a) $150.0 million and (b) the aggregate principal amount of all voluntary prepayments of term loans made prior to the date of incurrence of such additional term loan facilities and/or increases to the revolving commitments. The Lenders will have an opportunity to, but are not required to participate in the additional term loan facilities and/or revolving commitment increases. If the Lenders do not agree to provide such incremental facilities, the Company may request such additional and/or increased facilities from additional lenders. Interest on loans made under the Amended and Restated Credit Agreement in U.S. Dollars accrues, at Semtech’s option, at a rate per annum equal to (1) the New Base Rate (as defined below) plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) LIBOR (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio (such margin, the “New Applicable Margin”). The initial interest margin will be 2.00% for Base Rate loans and 1.00% for LIBOR rate loans, applicable until 2 business days following delivery of a compliance certificate by Semtech to the administrative agent with respect to the first fiscal period ending after the Closing Date. The “New Base Rate” is equal to a fluctuating rate equal to the highest of (a) the prime rate of the administrative agent, (b) ½ of 1% above the federal funds effective rate published by the Federal Reserve Bank of New York and (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1.00% . Interest on loans made under the Amended and Restated Credit Agreement in alternative currencies accrues at a rate per annum equal to LIBOR (determined with respect to deposits in the applicable alternative currency) (other than loans made in Canadian Dollars, for which a special reference rate for Canadian Dollars applies) for an interest period to be selected by Semtech plus the New Applicable Margin. Commitment fees on the unused portion of the revolving commitments accrue at a rate per annum ranging from 0.20% to 0.45% depending upon Semtech’s consolidated leverage ratio, provided the initial commitment fee shall be 0.40% per annum, applicable until 2 business days following delivery of a compliance certificate by Semtech to the administrative agent with respect to the first fiscal period ending after the Closing Date. With respect to letters of credit, Semtech will pay the administrative agent, for the account of the lenders under the revolving credit facility, letter of credit participation fees at a rate per annum equal to the applicable margin then in effect with respect to LIBOR-based loans under the revolving commitments on the face amount of all outstanding letters of credit. Semtech will also pay HSBC Bank USA, N.A., as the issuing bank, a fronting fee for each letter of credit issued under the Amended and Restated Credit Agreement at a rate equal to 0.125% per annum based on the maximum amount available to be drawn under each such letter of credit, as well as its customary documentation fees. All obligations of Semtech under the Amended and Restated Credit Agreement are unconditionally guaranteed by each of the Guarantors, which currently consist of all of the direct and indirect domestic subsidiaries of Semtech. Semtech and the Guarantors have also pledged substantially all of their assets to secure their obligations under the Amended and Restated Credit Agreement, including Semtech’s owned real property located in Camarillo, California. The outstanding principal balance of the term loans will be subject to repayment in quarterly installments beginning on the last day of Semtech’s fiscal quarter ending closest to January 31, 2017 in an amount equal to $3,750,000 per quarter for the first two years after the Closing Date, $4,697,500 per quarter in the third and fourth years following the Closing Date, and $5,625,000 per quarter in the fifth year following the Closing Date, with the balance being due at maturity on November 12, 2021. No amortization is required with respect to the revolving credit facility. Semtech may voluntarily prepay borrowings under the Amended and Restated Credit Agreement at any time and from time to time, without premium or penalty, other than customary “breakage costs” and fees for LIBOR-based loans. The term loans must be mandatorily prepaid using the proceeds of certain dispositions of assets and receipt of insurance proceeds, subject to agreed-upon thresholds and exceptions and customary reinvestment rights. The Amended and Restated Credit Agreement contains customary covenants, including limitations on Company’s ability to, among other things, incur indebtedness, create liens on assets, engage in certain fundamental corporate changes, make investments, sell or otherwise dispose of assets, repurchase stock, pay dividends or make similar distributions, engage in certain transactions with affiliates and make capital expenditures. In addition, the Company must comply with the following financial covenants, tested at the end of each fiscal quarter on a trailing four-quarter basis: (i) a minimum consolidated interest coverage ratio of 3.00 to 1.00 and (ii) a maximum consolidated leverage ratio of 3.00 to 1.00 provided that, such maximum consolidated leverage ratio may be increased to 3.25 to 1.00 or 3.50 to 1.00, as applicable, for the four consecutive fiscal quarters ending on or after the date of consummation of a permitted acquisition which constitutes a “Material Acquisition” under the Amended and Restated Credit Agreement, subject to the satisfaction of certain conditions.

Organization and Basis of Pre28

Organization and Basis of Presentation (Policy)	9 Months Ended
	Oct. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Fiscal Year	Fiscal Year The Company reports results on the basis of 52 and 53 week periods and ends its fiscal year on the last Sunday in January. The other quarters generally end on the last Sunday of April, July and October. All quarters consist of 13 weeks except for one 14 -week period in the fourth quarter of 53 -week years. The third quarter of fiscal years 2017 and 2016 each consisted of 13 weeks.
Principles of Consolidation	Principles of Consolidation The accompanying interim unaudited condensed consolidated financial statements have been prepared by the Company, in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and the instructions to quarterly report on Form 10-Q under the Securities Exchange Act of 1934, as amended, and Article 10 of Regulation S-X. In the opinion of the Company, these unaudited statements contain all adjustments (consisting of normal recurring adjustments) necessary to present fairly, in all material respects, the financial position of the Company for the interim periods presented. All significant intercompany balances have been eliminated. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, and the Company believes that the included disclosures are adequate to make the information presented not misleading. The Company evaluated all subsequent events through the date these interim unaudited condensed consolidated financial statements were issued. On March 4, 2015, the Company completed the acquisition of Triune Systems, L.L.C. (“Triune”). On January 13, 2015, the Company completed the acquisition of selected assets from EnVerv, Inc. (“EnVerv”). The interim unaudited condensed consolidated financial statements include the results of income of Triune and EnVerv commencing as of the acquisition dates. These interim unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended January 31, 2016 . The results reported in these interim unaudited condensed consolidated financial statements should not be regarded as indicative of results that may be expected for any subsequent period or for the entire year.
Segment Information	Segment Information The Company’s Chief Executive Officer (“CEO”) has been identified as the Chief Operating Decision Maker (“CODM”) as defined by guidance regarding segment disclosures (see Note 14 for further discussion). In fiscal year 2016, the Company updated its assessment of its operations in light of its restructuring efforts (see Note 17 for further discussion) and strategic business decisions. Based on this assessment, at that time the Company had identified five operating segments in total. Four of the operating segments aggregated into one reportable segment, the Semiconductor Products Group. The remaining operating segment, the Systems Innovation Group (shown as “All others”), could not be aggregated with the other operating segments and did not meet the criteria for a separate reportable segment as defined by the guidance regarding segment disclosure. As a result, the financial activity associated with the Systems Innovation Group was reported separately from the Company’s Semiconductor Products Group. This separate reporting was included in the “All others” category. On August 5, 2016, the Company completed its divestiture of its Snowbush Intellectual Property (“Snowbush IP”) business (previously part of the Company’s Systems Innovation Group) to Rambus Inc. (“Rambus”) for a purchase price of $32.0 million in cash along with the opportunity to receive additional payments from Rambus through 2022 based upon a percentage of sales by Rambus of new products expected to be developed by Rambus from the disposed assets. Beginning in the third quarter of fiscal year 2017, the Company no longer has a Systems Innovation Group or an “All others” category
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Derivatives	Derivatives and Hedging Activities Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 815, Derivatives and Hedging, provides the disclosure requirements for derivatives and hedging activities with the intent to provide users of financial statements with an enhanced understanding of: (a) how and why an entity uses derivative instruments, (b) how the entity accounts for derivative instruments and related hedged items, and (c) how derivative instruments and related hedged items affect an entity’s financial position, financial performance, and cash flows. Further, qualitative disclosures are required that explain the Company’s objectives and strategies for using derivatives, as well as quantitative disclosures about the fair value of and gains and losses on derivative instruments, and disclosures about credit-risk-related contingent features in derivative instruments. As required by ASC 815, the Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. In accordance with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. The Company records all derivatives within the condensed consolidated balance sheets at fair value, with assets included in “Other current assets” and liabilities included in “Accrued liabilities”. The Company’s accounting treatment for these instruments is based on whether or not the instruments are designated as a hedging instrument. The Company is currently applying hedge accounting to all foreign currency derivatives
Recent Accounting Pronouncements	Recent Accounting Pronouncements On August 26, 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-15, “Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments.” The primary purpose of this ASU is to reduce the diversity in practice that has resulted from the lack of consistent principles on this topic. This ASU is effective for fiscal years beginning after December 15, 2017. This ASU will be effective for the Company as of the beginning of Fiscal 2019. Early adoption is permitted in any interim or annual period. The Company is in the process of determining the impact of the adoption of this guidance on its consolidated financial statements or notes thereto; however, it does not anticipate that the new guidance will have a significant impact on its consolidated financial statements. In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842), which will require that substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The new standard also will result in enhanced quantitative and qualitative disclosures, including significant judgments made by management, to provide greater insight into the extent of revenue and expense recognized and expected to be recognized from existing leases. The standard requires modified retrospective adoption and will be effective December 15, 2018, with early adoption permitted. The Company does not expect the adoption of this update to have a material impact on its consolidated financial statements. In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330) Related to Simplifying the Measurement of Inventory which will apply to all inventory except inventory that is measured using last-in, first-out (“LIFO”) or the retail inventory method. Inventory measured using first-in, first-out or average cost is covered by the new amendments. Inventory within the scope of the new guidance should be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. Subsequent measurement is unchanged for inventory measured using LIFO or the retail inventory method. The amendments will take effect for public business entities for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The new guidance should be applied prospectively, and earlier application is permitted as of the beginning of an interim or annual reporting period. The Company is currently assessing the impact this update will have on its consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which will require an entity to recognize revenue from the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance addresses, in particular, contracts with more than one performance obligation, as well as the accounting for some costs to obtain or fulfill a contract with a customer, and provides for additional disclosures with respect to revenues and cash flows arising from contracts with customers. Public entities are required to apply the amendments on either a full- or modified-retrospective basis for annual periods beginning after December 15, 2017 and for interim periods within those annual periods. This update will be effective for the Company beginning in the first quarter of fiscal year 2019. Early adoption is not permitted. The Company is currently assessing the basis of adoption and evaluating the impact of the adoption of the update on its consolidated financial statements.
Earnings Per Share	Basic earnings per common share is computed by dividing net income available to common stockholders by the weighted-average number of shares of common stock outstanding during the reporting period. Diluted earnings per common share incorporate the incremental shares issuable, calculated using the treasury stock method, upon the assumed exercise of stock options and the vesting of restricted stock.
Revenue Recognition	Revenue Recognition The Company recognizes product revenue when persuasive evidence of an arrangement exists, delivery has occurred, the fee is fixed or determinable and collectability is probable. Recovery of costs associated with product design and engineering services are recognized during the period in which services are performed. The product design and engineering recovery, when recognized, will be reported as a reduction to product development and engineering expense. Historically, these recoveries have not exceeded the cost of the related development efforts. The Company includes revenue related to technology licenses as part of “Net sales.” Historically, revenue from these arrangements has not been significant though it is part of the Company’s recurring ordinary business. The Company defers revenue recognition on shipment of products to certain customers, principally distributors, under agreements which provide for limited pricing credits or return privileges, until these products are sold through to end users or the return privileges lapse. For sales subject to certain pricing credits or return privileges, the amount of future pricing credits or inventory returns cannot be reasonably estimated given the relatively long period in which a particular product may be held by the customer. Therefore, the Company has concluded that sales to customers under these agreements are not fixed and determinable at the date of the sale and revenue recognition has been deferred. The Company estimates the deferred gross margin on these sales by applying an average gross profit margin to the actual gross sales. The average gross profit margin is calculated for each category of material using standard costs which is expected to approximate actual costs at the date of sale. The estimated deferred gross margins on these sales, where there are no outstanding receivables, are recorded on the condensed consolidated balance sheets under the heading of “Deferred revenue.” The Company records a provision for estimated sales returns in the same period as the related revenues are recorded. The Company bases these estimates on historical sales returns and other known factors. Actual returns could be different from Company estimates and current provisions for sales returns and allowances, resulting in future charges to earnings. There were no significant impairments of deferred cost of sales in the third quarters of fiscal years 2017 or 2016 . The Company records a provision for sales rebates in the same period as the related revenues are recorded. These estimates are based on sales activity during the period. Actual rebates given could be different from our estimates and current provisions for sales rebates, resulting in future charges to earnings. The estimated sales rebates for sales activity during the period where there are no outstanding receivables are recorded on the condensed consolidated balance sheets under the heading of “Accrued liabilities.” The portion of the estimated sales rebate where there are outstanding receivables is recorded on the balance sheet as a reduction to accounts receivable.
Share-based Compensation, Option and Incentive Plans	Grant Date Fair Values and Underlying Assumptions: Contractual Terms The Company uses the Black-Scholes pricing model to value stock options. The estimated fair value of restricted stock units, for which vesting is not linked to a market condition, is calculated based on the market price of the Company’s common stock on the date of grant. For restricted stock units that vest according to a market condition, the Company uses a Monte Carlo simulation model to value the award. Some of the restricted stock units granted in the first nine months of fiscal year 2017 and prior years are classified as liabilities rather than equity. For grants classified as equity, share-based compensation is measured at the grant date, based on the fair value of the award, and is recognized as an expense over the grantee’s requisite service period. For grants classified as liabilities, share-based compensation is measured at fair value at the end of each reporting period until the date of settlement, and is recognized as an expense over the grantee’s requisite service period. Expected volatilities are based on historical volatility using daily and monthly stock price observations.
Investments	Investments that have original maturities of three months or less are accounted for as cash equivalents. This includes money market funds, time deposits and United States (“U.S.”) government obligations. Temporary and long-term investments consist of government, bank and corporate obligations, with original maturity dates in excess of three months. Temporary investments have original maturities in excess of three months, but mature within twelve months of the balance sheet date. Long-term investments have original maturities in excess of twelve months. The Company determines the cost of securities sold based on the specific identification method. Realized gains or losses are reported in “Non-operating expense, net” within the unaudited condensed consolidated statements of income.
Fair Value of Financial Instruments	Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis The Company reduces the carrying amounts of its goodwill, intangible assets, long-lived assets and non-marketable equity securities to fair value when held for sale or determined to be impaired. Instruments Not Recorded at Fair Value on a Recurring Basis Some of the Company’s financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate fair value due to their liquid or short-term nature. Such financial assets and financial liabilities include: cash and cash equivalents, net receivables, certain other assets, accounts payable, accrued expenses, accrued personnel costs, and other current liabilities. The Triune Earn-out liability is valued utilizing estimates of annual revenue and operating income (Level 3 inputs) during a period of approximately two -years ending January 2018. These estimates represent inputs for which market data are not available and are developed using the best information available about the assumptions that market participants would use when pricing the liability. The Cycleo Earn-out liability (see “Earn-out Liability” in Note 12) is valued utilizing estimates of annual revenue and operating income (Level 3 inputs) during a four -year period ending April 2020. These estimates represent inputs for which market data are not available and are developed using the best information available about the assumptions that market participants would use when pricing the liability. The Company measures contingent earn-out liabilities at fair value on a recurring basis using significant unobservable inputs classified within Level 3 of the fair value hierarchy. The Company uses a Monte Carlo valuation method as a valuation technique to determine the value of the earn-out liability. The significant unobservable inputs used in the fair value measurements are revenue projections over the earn-out period, and the probability outcome percentages assigned to each scenario. Significant increases or decreases to either of these inputs in isolation would result in a significantly higher or lower liability, with a higher liability capped by the contractual maximum of the contingent earn-out obligation. Ultimately, the liability will be equivalent to the amount paid, and the difference between the fair value estimate and amount paid will be recorded in earnings. For both the Triune Earn-out and Cycleo Earn-out, these companies have business profiles comparable to a start-up company. Accordingly, their respective revenue projections are subject to significant revisions. This characteristic has resulted in volatile changes to the measurement of fair value of the Triune Earn-out since the time of the Triune acquisition. The Company reviews and re-assesses the estimated fair value of contingent consideration on a quarterly basis, and the updated fair value could differ materially from the previous estimates. Changes in the estimated fair value of the Company’s contingent earn-out liabilities related to the time component of the present value calculation are reported in “Interest expense” within the unaudited condensed consolidated statements of income. Adjustments to the estimated fair value related to changes in all other unobservable inputs are reported in operating income.
Goodwill	Goodwill is not amortized, but is tested for impairment using a two-step method on an annual basis and whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The recoverability of goodwill is measured at the reporting unit level by comparing the reporting unit’s carrying amount, including goodwill, to the fair market value of the reporting unit. Goodwill is allocated to three reporting units (Signal Integrity, Power and High Reliability and Wireless and Sensing) (see Note 14 ). The difference between the fair value and the carrying amount of these reporting units is one of several factors the Company will consider before reaching its conclusion about whether to perform the first step of the goodwill impairment test.
Product Warranties	The Company’s general warranty policy provides for repair or replacement of defective parts. In some cases, a refund of the purchase price is offered. In certain instances the Company has agreed to other or additional warranty terms, including indemnification provisions. The product warranty accrual reflects the Company’s best estimate of probable liability under its product warranties. The Company accrues for known warranty issues if a loss is probable and can be reasonably estimated, and accrues for estimated incurred but unidentified issues based on historical experience. Historically, warranty expense has been immaterial to the Company’s consolidated financial statements.
Variable Interest Entities	The Company analyzes its investments or other interests to determine whether it represents a variable interest in a variable interest entity (“VIE”). If so, the Company evaluates the facts to determine whether it is the primary beneficiary. The Company considers itself to be the primary beneficiary when it has both the power to direct activities of the VIE that most significantly impact the VIEs economic performance and the obligation to absorb losses from or the right to receive benefits of the VIE that could potentially be significant to the VIE.
Derivatives, Methods of Accounting, Hedging Derivatives	The effective portions of cash flow hedges are recorded in accumulated other comprehensive income (“AOCI”) until the hedged item is recognized in selling, general and administrative (“SG&A”) expense within the unaudited condensed consolidated statements of income when the underlying hedged expense is recognized. Any ineffective portions of cash flow hedges are recorded in “Non-operating (expense) income, net” within the Company’s unaudited condensed consolidated statements of income. The Company presents its derivative assets and liabilities at their gross fair values on the condensed consolidated balance sheets.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Oct. 30, 2016
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The Company’s allocation of the total purchase price for Triune is summarized below: (in thousands) At March 4, 2015 Current assets $ 877 Property, plant, and equipment, net 226 Core technologies 10,000 Customer relationships 2,000 Goodwill 49,384 Current liabilities (1,287 ) Earn-out liability (16,200 ) Total acquisition consideration $ 45,000

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Oct. 30, 2016
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Common Share	The computation of basic and diluted earnings per common share is as follows: Three Months Ended Nine Months Ended (in thousands, except per share amounts) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Net income $ 30,776 $ 10,704 $ 46,642 $ 10,250 Weighted average common shares outstanding - basic 65,549 65,117 65,331 65,920 Dilutive effect of options and restricted stock units 657 100 568 331 Weighted average common shares outstanding - diluted 66,206 65,217 65,899 66,251 Basic earnings per common share $ 0.47 $ 0.16 $ 0.71 $ 0.16 Diluted earnings per common share $ 0.46 $ 0.16 $ 0.71 $ 0.15 Anti-dilutive shares not included in the above calculations 989 3,728 1,498 2,392

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Oct. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocation Of Stock-Based Compensation	The following table summarizes pre-tax, share-based compensation included in the unaudited condensed consolidated statements of income for the three and nine months ended October 30, 2016 and October 25, 2015 . Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Revenue offset $ 3,669 $ — $ 3,669 $ — Cost of sales 360 197 1,108 1,071 Selling, general and administrative 3,965 2,933 12,001 6,006 Product development and engineering 1,401 1,987 4,420 6,320 Share-based compensation $ 9,395 $ 5,117 $ 21,198 $ 13,397 Net change in share-based compensation capitalized into inventory $ 124 $ (233 ) $ 106 $ 45
Summary Of Fair Value Assumptions, Stock Options	The following table summarizes the assumptions used in the Black-Scholes model to determine the fair value of stock options granted in the three and nine months ended October 30, 2016 and October 25, 2015 , respectively: Three Months Ended Nine Months Ended October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Expected lives, in years 4.2 4.2 4.1 - 4.5 4.2 - 4.3 Estimated volatility 32% 32% 32% 29% - 32% Dividend yield — — — — Risk-free interest rate 1.0% 1.3% 1.1% - 1.3% 1.24% - 1.29% Weighted average fair value on grant date $7.10 $4.80 $5.67 $6.09
Summary Of The Activity For Stock Option Awards	The following table summarizes the activity for stock options for the nine months ended October 30, 2016 : (in thousands, except for per share amounts) Number of Shares Weighted Average Exercise Price (per share) Aggregate Intrinsic Value Aggregate Unrecognized Compensation Number of Shares Exercisable Weighted Average Contractual Term (in years) Balance at January 31, 2016 1,507 $ 25.18 $ 962 $ 3,748 775 Options granted 356 20.58 Options exercised (86 ) 19.17 482 Options cancelled/forfeited (95 ) 22.10 Balance at October 30, 2016 1,682 $ 24.69 $ 3,419 $ 3,796 902 Exercisable at October 30, 2016 902 $ 26.30 $ 873 2.3
Summary Of The Activity For Employee Stock Unit Awards	The following table summarizes the employees’ restricted stock unit activity for the nine months ended October 30, 2016 : (in thousands, except for per unit amounts) Number of Units Weighted Average Grant Date Fair Value (per unit) Aggregate Intrinsic Value (1) Aggregate Unrecognized Compensation Weighted Average Period Over Which Expected to be Recognized (in years) Balance at January 31, 2016 2,032 $ 23.70 $ 35,692 2.4 Restricted stock units granted 1,147 21.76 Restricted stock units vested (714 ) 25.28 $ 16,134 Restricted stock units forfeited (270 ) 20.77 Balance at October 30, 2016 2,195 $ 22.53 $ 41,348 2.6 (1) Reflects the value of Semtech Corporation stock on the date that the restricted stock unit vested.
Summary Of The Activity For Warrants	The following table summarizes the underlying Warrant Shares issued to Comcast for the nine months ended October 30, 2016 : (in thousands, except for per Warrant Share amounts) Number of Warrant Shares Weighted Average Grant Date Fair Value (per Warrant Share) Aggregate Intrinsic Value (1) Aggregate Unrecognized Expense Balance at January 31, 2016 — $ — — $ — Warrant shares granted 1,087 27.74 Warrant shares vested (109 ) 27.74 $ 3,015 Change in value — — 23,674 Balance at October 30, 2016 978 $ 27.74 $ 23,674
Performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary Of The Activity For Performance Unit Awards	The following table summarizes the activity for performance-based restricted stock units for the nine months ended October 30, 2016 : Subject to Share Settlement Subject to Cash Settlement Weighted Average Grant Date Fair Value (per unit) Aggregate Unrecognized Compensation Weighted Average Period Over Which Expected to be Recognized (in years) (in thousands, except for per unit amounts) Total Units Units Units Recorded Liability Balance at January 31, 2016 384 203 181 $ 237 $ 26.57 $ 1,925 1.5 Performance-based units granted 231 116 115 17.51 Performance-based units vested — — — — Performance-based units cancelled/forfeited (12 ) (6 ) (6 ) 17.51 Change in liability 621 Balance at October 30, 2016 603 313 290 $ 858 $ 23.29 $ 7,989 1.3
Market performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary Of The Activity For Performance Unit Awards	The following table summarizes the activity for market performance restricted stock units for the nine months ended October 30, 2016 : Weighted Average Grant Date Fair Value (per unit) Aggregate Unrecognized Compensation Period Over Which Expected to be Recognized (in years) (in thousands, except for per unit amounts) Total Units Balance at January 31, 2016 220 $ 15.59 $ 143 0.1 Market performance units granted — — Market performance units vested — — Market performance units cancelled/forfeited — — Balance at October 30, 2016 220 $ 15.59 $ — 0.0
Subject To Cash Settlement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary Of The Activity For Non-Employee Directors Stock Unit Awards	The following table summarizes the non-employee directors’ activity for restricted stock units settled in cash for the nine months ended October 30, 2016 : (in thousands, except for per unit amounts) Number of Units Recorded Liability Weighted Average Grant Date Fair Value (per unit) Aggregate Unrecognized Compensation Period Over Which Expected to be Recognized (in years) Balance at January 31, 2016 28 $ 3,870 $ 19.70 $ 221 0.4 Restricted stock units granted 25 23.40 Restricted stock units vested (30 ) 19.65 Restricted stock units forfeited — — Change in liability 502 Balance at October 30, 2016 23 $ 4,372 $ 23.67 $ 403 0.6
Subject To Share Settlement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary Of The Activity For Non-Employee Directors Stock Unit Awards	The following table summarizes the non-employee directors’ activity for restricted stock units settled with stock for the nine months ended October 30, 2016 : (in thousands, except for per unit amounts) Number of Units Weighted Average Grant Date Fair Value (per unit) Aggregate Intrinsic Value (1) Aggregate Unrecognized Compensation Period Over Which Expected to be Recognized (in years) Balance at January 31, 2016 24 $ 19.70 $ 186 0.4 Restricted stock units granted 21 23.40 Restricted stock units vested (25 ) 24.16 $ 616 Restricted stock units forfeited — — Balance at October 30, 2016 20 $ 23.67 $ 312 0.6 (1) Reflects the value of Semtech Corporation stock on the date that the restricted stock unit vested.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Oct. 30, 2016
Investments [Abstract]
Summary Of Investments	The following table summarizes the Company’s available-for-sale investments: October 30, 2016 January 31, 2016 (in thousands) Market Value Adjusted Cost Gross Unrealized Gain Market Value Adjusted Cost Gross Unrealized Gain Cash equivalents $ 16,908 $ 16,908 $ — $ 16,866 $ 16,866 $ — Total investments $ 16,908 $ 16,908 $ — $ 16,866 $ 16,866 $ —
Schedule Of Investments, Classified By Maturity Period	The following table summarizes the maturities of the Company’s available-for-sale investments: October 30, 2016 January 31, 2016 (in thousands) Market Value Adjusted Cost Market Value Adjusted Cost Within 1 year $ 16,908 $ 16,908 $ 16,866 $ 16,866 After 1 year through 5 years — — — — Total investments $ 16,908 $ 16,908 $ 16,866 $ 16,866
Summary Of Unrealized Gains (Losses) On Investments	The following table summarizes net unrealized losses arising in the periods presented in addition to the tax associated with these comprehensive income items: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Unrealized gain (loss), net of tax $ — $ 129 $ (85 ) $ 266 Increase to deferred tax liability — 74 — 172
Schedule of Cost Method Investments	The Company has the following investments which are accounted for as cost method investments: Entity Name Investment Value (in thousands) October 30, 2016 January 31, 2016 MultiPhy Ltd. $ 14,000 $ 12,000 Skorpios Technologies Inc. 3,000 3,000 Guangdong Dapu Telecom Technology Co., Ltd. 3,300 3,300 Senet, Inc. 1,900 1,900 Jariet Technologies Inc. — — Total $ 22,200 $ 20,200

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Oct. 30, 2016
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Financial assets and liabilities measured and recorded at fair value on a recurring basis were presented within the Company’s condensed consolidated balance sheets as follows: Fair Value as of October 30, 2016 Fair Value as of January 31, 2016 (in thousands) Total (Level 1) (Level 2) (Level 3) Total (Level 1) (Level 2) (Level 3) Financial assets: Cash equivalents $ 16,908 $ 16,908 $ — $ — $ 16,866 $ 16,866 $ — $ — Derivative financial instruments 215 — 215 — — — — — Total financial assets $ 17,123 $ 16,908 $ 215 $ — $ 16,866 $ 16,866 $ — $ — Financial liabilities: Triune Earn-out $ — $ — $ — $ — $ — $ — $ — $ — Cycleo Earn-out 1,295 — — 1,295 1,457 — — 1,457 Derivative financial instruments 445 — 445 — — — — — Total financial liabilities $ 1,740 $ — $ 445 $ 1,295 $ 1,457 $ — $ — $ 1,457
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation	A reconciliation of the change in the earn-out liability during the nine months ended October 30, 2016 is as follows: (in thousands) Cycleo Triune Total Balance at January 31, 2016 $ 1,457 $ — $ 1,457 Changes in the fair value of contingent earn-out obligations (162 ) — (162 ) Balance as of October 30, 2016 $ 1,295 $ — $ 1,295

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Oct. 30, 2016
Inventory Disclosure [Abstract]
Summary Of Inventories	Inventories, consisting of material, material overhead, labor, and manufacturing overhead, are stated at the lower of cost (first-in, first-out) or market and consist of the following: (in thousands) October 30, 2016 January 31, 2016 Raw materials $ 3,342 $ 2,094 Work in progress 40,731 40,940 Finished goods 18,606 20,841 Inventories $ 62,679 $ 63,875

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Oct. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Amounts of Goodwill	Changes in the carrying amount of goodwill were as follows: (in thousands) Signal Integrity Power and High Reliability Wireless and Sensing Total Balance at January 31, 2016 $ 261,891 $ 49,384 $ 18,428 $ 329,703 Additions — — — — Balance at October 30, 2016 $ 261,891 $ 49,384 $ 18,428 $ 329,703
Schedule of Finite-Lived Intangible Assets	The following table sets forth the Company’s finite-lived intangible assets resulting from business acquisitions and technology licenses purchased, which continue to be amortized: October 30, 2016 January 31, 2016 (in thousands) Estimated Useful Life Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Core technologies 5-8 years $ 144,930 $ (87,753 ) $ 57,177 $ 148,210 $ (74,006 ) $ 74,204 Customer relationships 5-10 years 30,030 (19,147 ) 10,883 30,030 (15,847 ) 14,183 Technology licenses (1) 2 years 100 (96 ) 4 100 (57 ) 43 Other intangibles assets 1-5 years 6,600 (6,600 ) — 6,600 (6,600 ) — Total finite-lived intangible assets $ 181,660 $ (113,596 ) $ 68,064 $ 184,940 $ (96,510 ) $ 88,430 (1) Technology licenses relate to end-license agreements for intellectual property that is used by the Company in research and development activities and also has alternative future uses. Amortization expense related to technology licenses is reported as “Product development and engineering” within the unaudited condensed consolidated statements of income.
Future Amortization Expense for Intangible Assets	The estimated annual amount of future amortization expense for all finite-lived intangible assets will be as follows: (in thousands) To be recognized in: Core Technologies Customer Relationships Technology Licenses Total Remaining three months of fiscal year 2017 $ 5,188 $ 1,100 $ 4 $ 6,292 Fiscal year 2018 20,744 4,400 — 25,144 Fiscal year 2019 17,332 4,400 — 21,732 Fiscal year 2020 9,905 950 — 10,855 Fiscal year 2021 3,056 33 — 3,089 Thereafter 952 — — 952 Total expected amortization expense $ 57,177 $ 10,883 $ 4 $ 68,064

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Oct. 30, 2016
Income Tax Disclosure [Abstract]
Summary of Income Tax Contingencies	A reconciliation of the beginning and ending amount of net unrecognized tax benefits is as follows: (in thousands) Balance at January 31, 2016 $ 8,432 Additions based on tax positions related to the current year 80 Reductions for tax positions of prior years, net (121 ) Reductions for settlements with tax authorities — Balance as of October 30, 2016 $ 8,391
Liability For Uncertain Tax Positions	The liability for UTP is reflected within the condensed consolidated balance sheets as follows: (in thousands) October 30, 2016 January 31, 2016 Deferred tax assets - non-current $ 7,121 $ 7,162 Other long-term liabilities 1,270 1,270 Total accrued taxes $ 8,391 $ 8,432

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Oct. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Environmental Loss Contingencies by Contingency	Therefore, the Company has recorded the minimum amount of probable loss as follows within the Company’s condensed consolidated balance sheets. (in thousands) Accrued Liability Other-Long Term Liability Total Balance at January 31, 2016 $ 1,150 $ 4,180 $ 5,330 Change in estimate (499 ) 499 — Utilization (116 ) — (116 ) Balance at October 30, 2016 $ 535 $ 4,679 $ 5,214
Summary of Earn-out Liabilities by Classification	A summary of earn-out liabilities by classification follows: Balance at October 30, 2016 Balance at January 31, 2016 (in thousands) Cycleo Triune Total Cycleo Triune Total Compensation expense $ 6,379 $ — $ 6,379 $ 4,397 $ — $ 4,397 Not conditional upon continued employment 1,295 — 1,295 1,457 — 1,457 Interest expense 590 — 590 405 — 405 Total liability $ 8,264 $ — $ 8,264 $ 6,259 $ — $ 6,259 Amount expected to be settled within twelve months $ 1,829 $ — $ 1,829 $ 2,155 $ — $ 2,155

Concentration of Risk (Tables)

Concentration of Risk (Tables)	9 Months Ended
	Oct. 30, 2016
Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Schedule Of Significant Customers Accounting For At Least 10% Of Net Sales or Receivables	The following significant customers accounted for at least 10% of net sales in one or more of the periods indicated: Three Months Ended Nine Months Ended (percentage of net sales) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Arrow (and affiliates) 11 % 10 % 9 % 9 %

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Oct. 30, 2016
Segment Reporting Information [Line Items]
Net Sales by Segment	Net sales by segment are as follows: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Semiconductor Products Group $ 137,185 $ 115,795 $ 404,036 $ 369,690 All others — 15 205 1,920 Total $ 137,185 $ 115,810 $ 404,241 $ 371,610
Income (loss) by Segment and Reconciliation to Consolidated Operating Income	Income by segment and reconciliation to consolidated operating income: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Semiconductor Products Group $ 33,013 $ 22,019 $ 92,973 $ 70,054 All others 25,214 (1,818 ) 22,738 (6,375 ) Operating Income by segment 58,227 20,201 115,711 63,679 Items to reconcile segment operating income to consolidated income before taxes Intangible amortization and impairments 6,286 6,308 19,017 18,648 Share-based compensation 9,395 5,117 21,199 13,397 Changes in the fair value of contingent earn-out obligations — (14,186 ) (162 ) (13,618 ) Restructuring charges — 962 — 4,526 Environmental reserve — — — 2,855 Other non-segment related (income) expenses 3,139 2,792 5,938 10,073 Amortization of fair value adjustments related to acquired PP&E 308 310 925 948 Interest expense, net 1,890 1,964 5,857 5,698 Non-operating expense, net 690 777 871 1,152 Income before taxes $ 36,519 $ 16,157 $ 62,066 $ 20,000
Net Sales Activity By Product Line	The table below provides net sales activity by product line on a comparative basis for all periods. Three Months Ended Nine Months Ended (in thousands, except percentages) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Signal Integrity $ 60,550 44 % $ 52,449 45 % $ 193,745 48 % $ 165,780 44 % Protection 40,250 29 % 33,225 29 % 108,296 27 % 105,339 28 % Wireless and Sensing 24,070 18 % 16,567 14 % 60,514 15 % 54,898 15 % Power and High-Reliability 15,984 12 % 13,554 12 % 45,150 11 % 43,673 12 % Systems Innovation — — % 15 — % 205 — % 1,920 1 % Other: Warrant Shares (3,669 ) (3 )% — — % (3,669 ) (1 )% — — % Total net sales $ 137,185 100 % $ 115,810 100 % $ 404,241 100 % $ 371,610 100 %
Net Sales Activity By Geographic Region	Net sales activity by geographic region is as follows: Three Months Ended Nine Months Ended October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Asia-Pacific 80 % 70 % 79 % 72 % North America 16 % 20 % 16 % 18 % Europe 7 % 10 % 8 % 10 % Other: Warrant Shares (3 )% — % (3 )% — % 100 % 100 % 100 % 100 %
Summary Of Sales Activity To Countries That Represented Greater Than 10% Of Total Net Sales	The table below summarizes sales activity to countries that represented greater than 10% of total net sales for one or more of the periods presented: Three Months Ended Nine Months Ended (percentage of total sales) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 China (including Hong Kong) 46 % 45 % 45 % 44 % United States 11 % 14 % 11 % 12 % Other: Warrant Shares (3 )% — % (3 )% — %
Income (Loss) From Continuing Operations Before Income Taxes	The Company’s regional income (loss) from continuing operations before income taxes is as follows: Three Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Domestic $ 937 $ 21,146 $ (13,048 ) $ 3,785 Canada 31,385 2,440 49,302 16,494 United Kingdom 3,568 4,984 14,150 17,328 Switzerland 764 (13,411 ) 7,791 (5,063 ) Japan 344 1,424 2,470 2,486 Other Foreign (479 ) (426 ) 1,401 (15,030 ) Total $ 36,519 $ 16,157 $ 62,066 $ 20,000

Stock Repurchase Program (Table

Stock Repurchase Program (Tables)	9 Months Ended
	Oct. 30, 2016
Equity [Abstract]
Class of Treasury Stock	The following table summarizes activity under the repurchase program for the three and nine month periods listed below: Three Months Ended Nine Months Ended October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 (in thousands, except number of shares) Shares Value Shares Value Shares Value Shares Value Repurchase Program expenditures — $ — 491,316 $ 7,464 23,968 $ 538 2,681,476 $ 57,311

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Oct. 30, 2016
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost	The following table summarizes the restructuring activity for the nine months ended October 30, 2016 : (in thousands) One-time employee termination benefits Balance at January 31, 2016 $ 342 Adjustments — Cash payments (336 ) Balance at October 30, 2016 $ 6

Derivatives and Hedging Activ42

Derivatives and Hedging Activities (Tables)	9 Months Ended
	Oct. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Open Foreign Currency Contracts	At October 30, 2016 , the Company had the following outstanding foreign exchange contracts: (in thousands) Foreign Exchange Contracts Number of Instruments Buy Notional Value Sell Notional Value Sell USD/Buy CHF Forward Contract 3 Fr. 2,672 $ 2,732 Sell USD/Buy CAD Forward Contract 3 C$ 6,337 $ 4,532 Sell USD/Buy GBP Forward Contract 15 £ 10,744 $ 13,568 Total 21
Summary of the Carrying Values of Derivative Instruments	The table below summarizes the carrying values of derivative instruments as of October 30, 2016 and January 31, 2016 : Carrying Values of Derivative Instruments as of October 30, 2016 (in thousands) Fair Value - Assets (2) Fair Value - (Liabilities) (2) Derivative Net Carrying Value Derivatives designated as hedging instruments Foreign exchange contracts (1) $ 215 $ (445 ) $ (230 ) Total derivatives $ 215 $ (445 ) $ (230 ) Carrying Values of Derivative Instruments as of January 31, 2016 Fair Value - Assets (2) Fair Value - (Liabilities) (2) Derivative Net Carrying Value Derivatives designated as hedging instruments Foreign exchange contracts (1) $ — $ — $ — Total derivatives $ — $ — $ — (1) Assets are included in “Other current assets” and liabilities are included in “Accrued liabilities” within the condensed consolidated balance sheets. (2) The fair values of the foreign exchange forward contracts are valued using Level 2 inputs. Please refer to Note 7 .
Summary of Gain (Loss) Recognized From Derivative Instruments	The following table summarizes the amount of income recognized from derivative instruments for the three months ended October 30, 2016 and October 25, 2015 as well as the line items within the accompanying unaudited condensed consolidated statements of income where the results are recorded for cash flow hedges: Amount of Gain (Loss) Recognized in AOCI on Derivative (Effective Portion) Location of Gain or Loss into Income (Effective Portion) Amount of (Gain) Loss Reclassified from AOCI into Income (Effective Portion) Location of Gain or Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Three Months Ended Three Months Ended Three Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Sell USD/Buy CHF Forward Contract $ (85 ) $ — SG&A $ (24 ) $ — SG&A $ (1 ) $ — Sell USD/Buy CAD Forward Contract (141 ) — SG&A (334 ) — SG&A — — Sell USD/Buy GBP Forward Contract (196 ) — SG&A 270 — SG&A (2 ) — $ (422 ) $ — $ (88 ) $ — $ (3 ) $ — The following table summarizes the amount of income recognized from derivative instruments for the nine months ended October 30, 2016 and October 25, 2015 as well as the line items within the accompanying unaudited condensed consolidated statements of income where the results are recorded for cash flow hedges: Amount of Gain (Loss) Recognized in AOCI on Derivative (Effective Portion) Location of Gain or Loss into Income (Effective Portion) Amount of (Gain) Loss Reclassified from AOCI into Income (Effective Portion) Location of Gain or Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Nine Months Ended Nine Months Ended Nine Months Ended (in thousands) October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 October 30, 2016 October 25, 2015 Sell USD/Buy CHF Forward Contract $ 51 $ — SG&A $ (72 ) $ — SG&A $ — $ — Sell USD/Buy CAD Forward Contract 1,113 — SG&A (909 ) — SG&A 5 — Sell USD/Buy GBP Forward Contract (843 ) — SG&A 435 — SG&A (3 ) — $ 321 $ — $ (546 ) $ — $ 2 $ —

Organization and Basis of Pre43

Organization and Basis of Presentation (Fiscal Year) (Details)	3 Months Ended		9 Months Ended
	Oct. 30, 2016weeks	Oct. 25, 2015weeks	Oct. 30, 2016weeksweek
52 Week Fiscal Year [Member]
Organization And Basis Of Presentation [Line Items]
Number of weeks in the fiscal year reporting period			52
Number of weeks in a quarter for 52 week fiscal period	13	13	13
53 Week Fiscal Year [Member]
Organization And Basis Of Presentation [Line Items]
Number of weeks in the fiscal year reporting period			53
Number of weeks in the 4th quarter for 53 week fiscal period | week			14

Organization and Basis of Pre44

Organization and Basis of Presentation (Segment Information) (Details) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended
	Oct. 30, 2016operating_segment	Jul. 31, 2016operating_segment	Oct. 30, 2016reportable_segment	Aug. 05, 2016USD ($)
Organization And Basis Of Presentation [Line Items]
Number of operating segments | operating_segment	4	5
Number of operating segments that aggregate into one reportable segment			4
Number of reportable segments			1
Systems Innovation [Member] | Snowbush IP Business [Member]
Organization And Basis Of Presentation [Line Items]
Cash consideration received related to divestiture | $				$ 32

Acquisitions (Details)

Acquisitions (Details) - USD ($)	Mar. 04, 2015	Jan. 13, 2015	Sep. 30, 2015	Jul. 31, 2016	Oct. 30, 2016	Oct. 25, 2015	Jan. 31, 2016	Jan. 25, 2015
Business Acquisition [Line Items]
Effective date of acquisition	Mar. 4, 2015	Jan. 13, 2015
Name of acquired entity	Triune Systems, L.L.C.	EnVerv
Borrowings under line of credit	$ 35,000,000				$ 0	$ 35,000,000
Potential payments under earn-out arrangements, high estimate	70,000,000
Goodwill					329,703,000		$ 329,703,000
Triune Systems [Member]
Business Acquisition [Line Items]
Purchase price	45,000,000
Cash paid to to acquire business	35,000,000		$ 9,500,000	$ 500,000
Additional cash consideration	10,000,000
Goodwill	49,384,000
Earn-out liability					$ 0
Triune Systems [Member] | Core Technologies [Member]
Business Acquisition [Line Items]
Acquisition consideration allocated to finite-lived intangible assets	10,000,000
Triune Systems [Member] | Earn-out Payable Within First Three Fiscal Years Of Acquisition Date [Member]
Business Acquisition [Line Items]
Period over which contingent consideration will be paid					2 years
Triune Systems [Member] | Additional Earn-out Payable After Third Fiscal Year From Acquisition Date [Member]
Business Acquisition [Line Items]
Potential payments under earn-out arrangements, high estimate	$ 16,000,000
EnVerv [Member]
Business Acquisition [Line Items]
Cash paid to to acquire business		$ 4,900,000
Goodwill								$ 3,400,000
EnVerv [Member] | Core Technologies [Member]
Business Acquisition [Line Items]
Acquisition consideration allocated to finite-lived intangible assets								$ 1,400,000

Acquisitions - Triune Purchase

Acquisitions - Triune Purchase Price Allocation (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016	Mar. 04, 2015
Business Acquisition [Line Items]
Goodwill	$ 329,703	$ 329,703
Earn-out liability	(8,264)	(6,259)
Triune Systems [Member]
Business Acquisition [Line Items]
Current assets			$ 877
Property, plant, and equipment, net			226
Goodwill			49,384
Current liabilities			(1,287)
Earn-out liability	$ 0	$ 0	(16,200)
Total acquisition consideration			45,000
Core Technologies [Member] | Triune Systems [Member]
Business Acquisition [Line Items]
Amortizable intangible assets			10,000
Customer Relationships [Member] | Triune Systems [Member]
Business Acquisition [Line Items]
Amortizable intangible assets			$ 2,000

Earnings Per Share - Computatio

Earnings Per Share - Computation Of Basic And Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Earnings Per Share [Abstract]
Net income	$ 30,776	$ 10,704	$ 46,642	$ 10,250
Weighted average common shares outstanding - basic	65,549	65,117	65,331	65,920
Dilutive effect of options and restricted stock units	657	100	568	331
Weighted average common shares outstanding - diluted	66,206	65,217	65,899	66,251
Basic earnings per common share (in dollars per share)	$ 0.47	$ 0.16	$ 0.71	$ 0.16
Diluted earnings per common share (in dollars per share)	$ 0.46	$ 0.16	$ 0.71	$ 0.15
Anti-dilutive shares not included in the above calculations	989	3,728	1,498	2,392

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands	Oct. 05, 2016USD ($)mod$ / sharesshares	Feb. 26, 2014$ / shares	Oct. 30, 2016USD ($)$ / sharesshares	Oct. 25, 2015	Oct. 30, 2016USD ($)$ / sharesshares	Oct. 25, 2015	Jan. 31, 2016USD ($)$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees affected by modification of awards					12
Incremental compensation cost resulting from modifications of stock awards | $			$ 0		$ 0		$ 0
Maximum number of shares subject to purchase under warrants | shares	1,086,957
Common stock, par value	$ 0.01		$ 0.01		$ 0.01		$ 0.01
Fair value of warrant shares | $	$ 30,000
Number of trading days in period used to determine average closing price applicable to Warrant Shares | d	10
Exercise price of warrants (per share)			$ 0.01		$ 0.01
Percent of warrants vested upon issuance	10.00%
Number of months in milestone period of warrants | mo	30
Warrants, contractual term	7 years
Reason for issuing warrants	The Warrant was issued by the Company to Comcast in connection with an agreement between the parties regarding the intended trial deployment by Comcast of a low-power wide-area Network (LPWAN) in the United States, based on the Company’s LoRa® Wireless Radio Frequency Technology.
Number of performance tranches of warrants	5
Warrants exercised | shares					0
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential per share consideration due upon change in control					$ 40
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected lives			4 years 2 months	4 years 2 months
Stock options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					3 years
Expected lives					4 years 1 month	4 years 2 months
Stock options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Expected lives					4 years 6 months	4 years 4 months
Performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value					$ 17.51
Market Performance Units, Tranche 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value		$ 17.26
Market Performance Units, Tranche 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value		$ 14.88
Market performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value					$ 0
Employee restricted stock unit awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Weighted average grant date fair value					$ 21.76
Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value					$ 27.74
Expected lives	7 years
Subject To Share Settlement [Member] | Non-employee director stock unit awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					1 year
Weighted average grant date fair value					$ 23.40
Subject To Cash Settlement [Member] | Non-employee director stock unit awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					1 year
Weighted average grant date fair value					$ 23.40
Vested but unsettled stock units | shares			173,657		173,657
Individuals Not Associated With EnVery Transaction [Member] | Performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					3 years
Performance condition, highest potential performance level					200.00%
Maximum number of shares which would be settled in shares | shares					582,032
Maximum number of shares which would be settled in cash | shares					582,032
Target performance metrics for performance unit awards, fiscal year 2017					190.00%
Target performance metrics for performance unit awards, fiscal year 2016					0.00%
Individuals Associated With EnVery Transaction [Member] | Performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Performance condition, highest potential performance level					100.00%
Maximum number of shares which would be settled in shares | shares					24,000
Award vesting percentage					25.00%
Number of shares to be issued for current fiscal year grants | shares					0
CEO [Member] | Market Performance Units, Tranche 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage		30.00%
Award performance period		120 days
CEO [Member] | Market Performance Units, Tranche 1 [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average per share closing price used to determine vesting rights (in dollars per share)		$ 35
CEO [Member] | Market Performance Units, Tranche 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period		120 days
CEO [Member] | Market Performance Units, Tranche 2 [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average per share closing price used to determine vesting rights (in dollars per share)		$ 40
Other Long-term Liabilities [Member] | Subject To Cash Settlement [Member] | Non-employee director stock unit awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation liability, long-term | $			$ 4,400		$ 4,400

Share-Based Compensation - Allo

Share-Based Compensation - Allocation of Share-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 9,395	$ 5,117	$ 21,198	$ 13,397
Inventories [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net change in share-based compensation capitalized into inventory	124	(233)	106	45
Revenue Offset [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	3,669	0	3,669	0
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	360	197	1,108	1,071
Selling, General and Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	3,965	2,933	12,001	6,006
Product Development And Engineering [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 1,401	$ 1,987	$ 4,420	$ 6,320

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Fair Value Assumptions (Details) - Stock options [Member] - $ / shares	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected lives	4 years 2 months	4 years 2 months
Estimated volatility	32.00%	32.00%	32.00%
Estimated volatility, minimum				29.00%
Estimated volatility, maximum				32.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	1.00%	1.30%
Risk-free interest rate, minimum			1.10%	1.24%
Risk-free interest rate, maximum			1.30%	1.29%
Weighted average fair value on grant date	$ 7.10	$ 4.80	$ 5.67	$ 6.09
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected lives			4 years 1 month	4 years 2 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected lives			4 years 6 months	4 years 4 months

Share-Based Compensation - Su51

Share-Based Compensation - Summary of the Activity for Stock Option Awards (Details) - Stock options [Member] $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Oct. 30, 2016USD ($)$ / sharesshares
Number of Shares
Beginning balance (in shares)	1,507
Options granted (in shares)	356
Options exercised (in shares)	(86)
Options cancelled/forfeited (in shares)	(95)
Ending balance (in shares)	1,682
Exercisable at end of period (in shares)	902
Weighted Average Exercise Price (per share)
Beginning balance | $ / shares	$ 25.18
Options granted | $ / shares	20.58
Options exercised | $ / shares	19.17
Options cancelled/forfeited | $ / shares	22.10
Ending balance | $ / shares	24.69
Exercisable at end of period (in dollars per share) | $ / shares	$ 26.30
Aggregate Intrinsic Value
Beginning balance | $	$ 962
Options exercised | $	482
Ending balance | $	3,419
Exercisable at end of period | $	873
Aggregate Unrecognized Compensation
Beginning balance | $	3,748
Ending balance | $	$ 3,796
Number of Shares Exercisable
Exercisable at beginning of period (in shares)	775
Exercisable at end of period (in shares)	902
Weighted Average Contractual Term (in years)
Exercisable at end of period	2 years 4 months

Share-Based Compensation - Su52

Share-Based Compensation - Summary of the Activity for Performance Unit Awards (Details) - Performance shares [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Oct. 30, 2016	Jan. 31, 2016
Units
Beginning balance (in shares)	384
Performance units granted (in shares)	231
Performance units vested (in shares)	0
Performance units cancelled/forfeited (in shares)	(12)
Ending balance (in shares)	603	384
Weighted Average Grant Date Fair Value (per share)
Beginning balance	$ 26.57
Performance units granted (in dollars per share)	17.51
Performance units vested (in dollars per share)	0
Performance units forfeited (in dollars per share)	17.51
Ending balance	$ 23.29	$ 26.57
Aggregate Unrecognized Compensation
Beginning balance	$ 1,925
Ending balance	$ 7,989	$ 1,925
Weighted Average Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized	1 year 4 months	1 year 6 months
Subject To Share Settlement [Member]
Units
Beginning balance (in shares)	203
Performance units granted (in shares)	116
Performance units vested (in shares)	0
Performance units cancelled/forfeited (in shares)	(6)
Ending balance (in shares)	313	203
Subject To Cash Settlement [Member]
Units
Beginning balance (in shares)	181
Performance units granted (in shares)	115
Performance units vested (in shares)	0
Performance units cancelled/forfeited (in shares)	(6)
Ending balance (in shares)	290	181
Recorded Liability
Beginning balance	$ 237
Change in liability	621
Ending balance	$ 858	$ 237

Share-Based Compensation - Su53

Share-Based Compensation - Summary of the Activity for Market Performance Units Awards (Details) - Market performance shares [Member] - USD ($) $ / shares in Units, shares in Thousands	9 Months Ended	12 Months Ended
	Oct. 30, 2016	Jan. 31, 2016
Units
Beginning balance (in shares)	220
Performance units granted (in shares)	0
Performance units vested (in shares)	0
Performance units cancelled/forfeited (in shares)	0
Ending balance (in shares)	220	220
Weighted Average Grant Date Fair Value (per share)
Beginning balance	$ 15.59
Performance units granted (in dollars per share)	0
Performance units vested (in dollars per share)	0
Performance units forfeited (in dollars per share)	0
Ending balance	$ 15.59	$ 15.59
Aggregate Unrecognized Compensation
Beginning balance	$ 143
Ending balance	$ 0	$ 143
Weighted Average Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized	0 years	1 month

Share-Based Compensation - Su54

Share-Based Compensation - Summary of the Activity for Employee Stock Unit Awards (Details) - Employee restricted stock unit awards [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		9 Months Ended	12 Months Ended
		Oct. 30, 2016	Jan. 31, 2016
Number of Units
Beginning balance (in shares)		2,032
Stock units granted (in shares)		1,147
Stock units vested (in shares)		(714)
Stock units forfeited (in shares)		(270)
Ending balance (in shares)		2,195	2,032
Weighted Averaged Grant Date Fair Value (per unit)
Beginning balance		$ 23.70
Stock units granted (in dollars per share)		21.76
Stock units vested (in dollars per share)		25.28
Stock units forfeited (in dollars per share)		20.77
Ending balance		$ 22.53	$ 23.70
Aggregate Intrinsic Value
Aggregate intrinsic value of stock units vested	[1]	$ 16,134
Aggregate Unrecognized Compensation
Beginning balance		35,692
Ending balance		$ 41,348	$ 35,692
Weighted Average Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized		2 years 7 months	2 years 5 months
[1]	Reflects the value of Semtech Corporation stock on the date that the restricted stock unit vested.

Share-Based Compensation - Su55

Share-Based Compensation - Summary of the Activity for Cash Settled Non-Employee Directors Stock Unit Awards (Details) - Subject To Cash Settlement [Member] - Non-employee director stock unit awards [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Oct. 30, 2016	Jan. 31, 2016
Number of Units
Beginning balance (in shares)	28
Stock units granted (in shares)	25
Stock units vested (in shares)	(30)
Stock units forfeited (in shares)	0
Ending balance (in shares)	23	28
Recorded Liability
Beginning balance	$ 3,870
Change in liability	502
Ending balance	$ 4,372	$ 3,870
Weighted Average Grant Date Fair Value (per unit)
Beginning balance	$ 19.70
Stock units granted (in dollars per share)	23.40
Stock units vested (in dollars per share)	19.65
Stock units forfeited (in dollars per share)	0
Ending balance	$ 23.67	$ 19.70
Aggregate Unrecognized Compensation
Beginning balance	$ 221
Ending balance	$ 403	$ 221
Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized	7 months	5 months

Share-Based Compensation - Su56

Share-Based Compensation - Summary of Activity for Stock Settled Non-Employee Directors Stock Unit Awards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015	Jan. 31, 2016
Weighted Average Grant Date Fair Value (per unit)
Increase to deferred tax liability		$ 0	$ 74	$ 0	$ 172
Subject To Share Settlement [Member] | Non-employee director stock unit awards [Member]
Number of Units
Beginning balance (in shares)				24
Stock units granted (in shares)				21
Stock units vested (in shares)				(25)
Stock units forfeited (in shares)				0
Ending balance (in shares)		20		20		24
Weighted Average Grant Date Fair Value (per unit)
Beginning balance				$ 19.70
Stock units granted (in dollars per share)				23.40
Stock units vested (in dollars per share)				24.16
Warrant shares forfeited (in dollars per share)				0
Ending balance		$ 23.67		$ 23.67		$ 19.70
Aggregate Intrinsic Value
Aggregate intrinsic value of stock units vested	[1]			$ 616
Aggregate Unrecognized Compensation
Beginning balance				186
Ending balance		$ 312		$ 312		$ 186
Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized				7 months		5 months
[1]	the value of Semtech Corporation stock on the date that the restricted stock unit vested.

Share-Based Compensation - Su57

Share-Based Compensation - Summary of Activity for Warrants (Details) - USD ($)		9 Months Ended
		Oct. 30, 2016	Jan. 31, 2016
Aggregate Intrinsic Value
Aggregate intrinsic value of warrant shares outstanding	[1]		$ 0
Aggregate Unrecognized Compensation
Change in value		$ 23,674,000
Warrant [Member]
Units
Beginning balance (in shares)		0
Warrants shares granted (in shares)		1,087,000
Warrants shares vested (in shares)		(109,000)
Ending balance (in shares)		978,000
Weighted Averaged Grant Date Fair Value (per unit)
Beginning balance		$ 0
Warrant shares granted (in dollars per share)		27.74
Warrant shares vested (in dollars per share)		27.74
Ending balance		$ 27.74
Aggregate Intrinsic Value
Aggregate intrinsic value of warrant shares vested	[1]	$ 3,015,000
Aggregate Unrecognized Compensation
Beginning balance		0
Ending balance		$ 23,674,000
[1]	Reflects the value of Semtech Corporation Warrant Shares on the date the Warrant Shares vested.

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Oct. 30, 2016	Jan. 31, 2016
Investment [Line Items]
Total cost method investment in privately traded companies	$ 22,200	$ 20,200
Minimum [Member]
Investment [Line Items]
Investment maturity period	3 months
Short-term Investments [Member] | Minimum [Member]
Investment [Line Items]
Investment maturity period	3 months
Short-term Investments [Member] | Maximum [Member]
Investment [Line Items]
Investment maturity period	12 months
Other Long-term Investments [Member] | Minimum [Member]
Investment [Line Items]
Investment maturity period	12 months
Other Assets [Member]
Investment [Line Items]
Total cost method investment in privately traded companies	$ 22,200	$ 20,200

Investments - Summary Of Invest

Investments - Summary Of Investments (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Investment [Line Items]
Available-for-sale securities, market value	$ 16,908	$ 16,866
Available-for-sale investments, adjusted cost	16,908	16,866
Available-for-sale investments, gross unrealized gain	0	0
Cash Equivalents [Member]
Investment [Line Items]
Available-for-sale securities, market value	16,908	16,866
Available-for-sale investments, adjusted cost	16,908	16,866
Available-for-sale investments, gross unrealized gain	$ 0	$ 0

Investments - Schedule Of Inves

Investments - Schedule Of Investments, Classified By Maturity Period (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Investment [Line Items]
Available-for-sale securities, market value	$ 16,908	$ 16,866
Available-for-sale investments, adjusted cost	16,908	16,866
Within 1 Year [Member]
Investment [Line Items]
Available-for-sale securities, market value	16,908	16,866
Available-for-sale investments, adjusted cost	16,908	16,866
After 1 Year Through 5 Years [Member]
Investment [Line Items]
Available-for-sale securities, market value	0	0
Available-for-sale investments, adjusted cost	$ 0	$ 0

Investments - Summary Of Unreal

Investments - Summary Of Unrealized Gains (Losses) On Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Investments [Abstract]
Unrealized gain (loss), net of tax	$ 0	$ 129	$ (85)	$ 266
Increase to deferred tax liability	$ 0	$ 74	$ 0	$ 172

Investments - Summary of Cost M

Investments - Summary of Cost Method Investments (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Schedule of Cost-method Investments [Line Items]
Total cost method investment in privately traded companies	$ 22,200	$ 20,200
MultiPhy Ltd [Member]
Schedule of Cost-method Investments [Line Items]
Total cost method investment in privately traded companies	14,000	12,000
Skorpios Technologies Inc [Member]
Schedule of Cost-method Investments [Line Items]
Total cost method investment in privately traded companies	3,000	3,000
Guangdong Dapu Telecom Technology Co., Ltd [Member]
Schedule of Cost-method Investments [Line Items]
Total cost method investment in privately traded companies	3,300	3,300
Senet, Inc [Member]
Schedule of Cost-method Investments [Line Items]
Total cost method investment in privately traded companies	1,900	1,900
Jariet Technologies Inc [Member]
Schedule of Cost-method Investments [Line Items]
Total cost method investment in privately traded companies	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Oct. 30, 2016	Jan. 31, 2016
Cycleo [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Period over which contingent consideration is valued	4 years
Earn-out Payable Within First Three Fiscal Years Of Acquisition Date [Member] | Triune Systems [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Period over which contingent consideration is valued	2 years
Level 2 [Member] | Term Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 67.8	$ 77.1
Level 2 [Member] | Revolving Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 181	$ 181

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative financial instruments (asset)	$ 215	$ 0
Total financial assets	17,123	16,866
Derivative financial instruments (liability)	445	0
Total financial liabilities	1,740	1,457
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative financial instruments (asset)	0	0
Total financial assets	16,908	16,866
Derivative financial instruments (liability)	0	0
Total financial liabilities	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative financial instruments (asset)	215	0
Total financial assets	215	0
Derivative financial instruments (liability)	445	0
Total financial liabilities	445	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative financial instruments (asset)	0	0
Total financial assets	0	0
Derivative financial instruments (liability)	0	0
Total financial liabilities	1,295	1,457
Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities	16,908	16,866
Cash Equivalents [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities	16,908	16,866
Cash Equivalents [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities	0	0
Cash Equivalents [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities	0	0
Triune Systems [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	0	0
Triune Systems [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	0	0
Triune Systems [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	0	0
Triune Systems [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	0	0
Not Conditional Upon Continued Employment [Member] | Cycleo [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	1,295	1,457
Not Conditional Upon Continued Employment [Member] | Cycleo [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	0	0
Not Conditional Upon Continued Employment [Member] | Cycleo [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	0	0
Not Conditional Upon Continued Employment [Member] | Cycleo [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Earn-out liability	$ 1,295	$ 1,457

Fair Value Measurements - Level

Fair Value Measurements - Level 3 Reconciliation of the Earn-out Liability (Details) $ in Thousands	9 Months Ended
	Oct. 30, 2016USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 1,457
Changes in the fair value of contingent earn-out obligations	(162)
Ending balance	1,295
Cycleo [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1,457
Changes in the fair value of contingent earn-out obligations	(162)
Ending balance	1,295
Triune Systems [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	0
Changes in the fair value of contingent earn-out obligations	0
Ending balance	$ 0

Inventories - Summary of Invent

Inventories - Summary of Inventories (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 3,342	$ 2,094
Work in progress	40,731	40,940
Finished goods	18,606	20,841
Inventories	$ 62,679	$ 63,875

Goodwill and Intangible Asset67

Goodwill and Intangible Assets - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016USD ($)	Oct. 25, 2015USD ($)	Oct. 30, 2016USD ($)reporting_unit	Oct. 25, 2015USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Number of reporting units | reporting_unit			3
Amortization expense related to finite-lived intangible assets	$ 6,286	$ 6,308	$ 19,017	$ 18,648
Indefinite-lived intangible assets	$ 0		$ 0

Goodwill and Intangible Asset68

Goodwill and Intangible Assets - Changes in Carrying Amounts of Goodwill (Details) $ in Thousands	9 Months Ended
	Oct. 30, 2016USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 329,703
Additions	0
Ending balance	329,703
Signal Integrity [Member]
Goodwill [Roll Forward]
Beginning balance	261,891
Additions	0
Ending balance	261,891
Power and High Reliability [Member]
Goodwill [Roll Forward]
Beginning balance	49,384
Additions	0
Ending balance	49,384
Wireless and Sensing [Member]
Goodwill [Roll Forward]
Beginning balance	18,428
Additions	0
Ending balance	$ 18,428

Goodwill and Intangible Asset69

Goodwill and Intangible Assets - Schedule Of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands		9 Months Ended
		Oct. 30, 2016	Jan. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		$ 181,660	$ 184,940
Accumulated amortization		(113,596)	(96,510)
Net carrying amount		68,064	88,430
Core Technologies [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		144,930	148,210
Accumulated amortization		(87,753)	(74,006)
Net carrying amount		$ 57,177	74,204
Core Technologies [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		5 years
Core Technologies [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		8 years
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		$ 30,030	30,030
Accumulated amortization		(19,147)	(15,847)
Net carrying amount		$ 10,883	14,183
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		5 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		10 years
Technology Licenses [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	[1]	2 years
Gross carrying amount	[1]	$ 100	100
Accumulated amortization	[1]	(96)	(57)
Net carrying amount	[1]	4	43
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		6,600	6,600
Accumulated amortization		(6,600)	(6,600)
Net carrying amount		$ 0	$ 0
Other Intangible Assets [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		1 year
Other Intangible Assets [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		5 years
[1]	Technology licenses relate to end-license agreements for intellectual property that is used by the Company in research and development activities and also has alternative future uses. Amortization expense related to technology licenses is reported as “Product development and engineering” within the unaudited condensed consolidated statements of income.

Goodwill and Intangible Asset70

Goodwill and Intangible Assets - Future Amortization Expense For Intangible Assets (Details) - USD ($) $ in Thousands		Oct. 30, 2016	Jan. 31, 2016
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining three months of fiscal year 2017		$ 6,292
Fiscal year 2018		25,144
Fiscal year 2019		21,732
Fiscal year 2020		10,855
Fiscal year 2021		3,089
Thereafter		952
Net carrying amount		68,064	$ 88,430
Core Technologies [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining three months of fiscal year 2017		5,188
Fiscal year 2018		20,744
Fiscal year 2019		17,332
Fiscal year 2020		9,905
Fiscal year 2021		3,056
Thereafter		952
Net carrying amount		57,177	74,204
Customer Relationships [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining three months of fiscal year 2017		1,100
Fiscal year 2018		4,400
Fiscal year 2019		4,400
Fiscal year 2020		950
Fiscal year 2021		33
Thereafter		0
Net carrying amount		10,883	14,183
Technology Licenses [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remaining three months of fiscal year 2017		4
Fiscal year 2018		0
Fiscal year 2019		0
Fiscal year 2020		0
Fiscal year 2021		0
Thereafter		0
Net carrying amount	[1]	$ 4	$ 43
[1]	Technology licenses relate to end-license agreements for intellectual property that is used by the Company in research and development activities and also has alternative future uses. Amortization expense related to technology licenses is reported as “Product development and engineering” within the unaudited condensed consolidated statements of income.

Credit Facilities - Narrative (

Credit Facilities - Narrative (Details)	Nov. 15, 2016USD ($)	Mar. 04, 2015USD ($)	May 02, 2013USD ($)	Oct. 30, 2016USD ($)	Oct. 25, 2015USD ($)
Borrowings under line of credit		$ 35,000,000		$ 0	$ 35,000,000
Minimum [Member]
Interest coverage ratio				3.50
Maximum [Member]
Total leverage ratio				3
Prior Credit Agreement [Member]
Facilities, maximum borrowing capacity			$ 400,000,000
Facilities, term			5 years
Prior Credit Agreement [Member] | Base Rate [Member]
Description of variable rate basis			the highest of (a) the prime rate (as published by The Wall Street Journal), (b) ½ of 1% above the federal funds effective rate or (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1%.
Prior Credit Agreement [Member] | Base Rate [Member] | Minimum [Member]
Basis spread on variable rate			0.25%
Prior Credit Agreement [Member] | Base Rate [Member] | Maximum [Member]
Basis spread on variable rate			1.25%
Prior Credit Agreement [Member] | LIBOR [Member]
Basis spread on variable rate			1.00%
Prior Credit Agreement [Member] | LIBOR [Member] | Minimum [Member]
Basis spread on variable rate			1.25%
Prior Credit Agreement [Member] | LIBOR [Member] | Maximum [Member]
Basis spread on variable rate			2.25%
Prior Credit Agreement [Member] | Federal Funds [Member]
Basis spread on variable rate			1.00%
Prior Credit Agreement [Member] | CDOR [Member]
Description of variable rate basis			the sum of: (a) the rate determined by Administrative Agent with reference to the arithmetic average of the discount rate quotations of all institutions listed for CAD Dollar-denominated bankers’ acceptances displayed and identified on the “Reuters Screen CDOR Page” and (b) 0.10% per annum
Basis spread on variable rate			0.10%
Prior Credit Agreement [Member] | CDOR [Member] | Minimum [Member]
Basis spread on variable rate			1.25%
Prior Credit Agreement [Member] | CDOR [Member] | Maximum [Member]
Basis spread on variable rate			2.25%
Prior Credit Agreement Term Loans [Member]
Facilities, maximum borrowing capacity			$ 150,000,000
Facilities, amount outstanding				$ 67,800,000
Facilities, Interest rate at period end				2.28%
Facilities, maturity date				May 1, 2018
Prior Credit Agreement Revolving Line of Credit [Member]
Facilities, maximum borrowing capacity			$ 250,000,000
Facilities, amount outstanding				$ 181,000,000
Facilities, Interest rate at period end				2.28%
Prior Credit Agreement Revolving Line of Credit [Member] | Minimum [Member]
Facilities, unused capacity, commitment fee percentage			0.20%
Prior Credit Agreement Revolving Line of Credit [Member] | Maximum [Member]
Facilities, unused capacity, commitment fee percentage			0.45%
Prior Credit Agreement Letter of Credit [Member]
Facilities, maximum borrowing capacity			$ 40,000,000
Facilities, amount outstanding				$ 0
Prior Credit Agreement Swingline Loans [Member]
Facilities, maximum borrowing capacity			$ 25,000,000
Facilities, amount outstanding				0
Alternative Currencies, Except Canadian [Member]
Description of variable rate basis			a rate per annum equal to LIBOR (determined with respect to deposits in the applicable Alternative Currency) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio.
Prior Credit Agreement Alternative Currencies Line of Credit [Member]
Facilities, maximum borrowing capacity			$ 40,000,000
Facilities, amount outstanding				$ 0
United States of America, Dollars | Prior Credit Agreement [Member]
Description of variable rate basis			(1) the Base Rate plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) LIBOR (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio.
Canada, Dollars | Prior Credit Agreement [Member]
Description of variable rate basis			a rate per annum equal to the CDOR Rate for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio.
Subsequent Event [Member] | New Credit Agreement Term Loans [Member]
Facilities, maximum borrowing capacity	$ 150,000,000
Facilities, amount outstanding	150,000,000
Subsequent Event [Member] | New Credit Agreement Revolving Line of Credit [Member]
Facilities, maximum borrowing capacity	250,000,000
Facilities, amount outstanding	$ 97,000,000
Facilities, unused capacity, commitment fee percentage	0.40%
Subsequent Event [Member] | New Credit Agreement Revolving Line of Credit [Member] | Minimum [Member]
Facilities, unused capacity, commitment fee percentage	0.20%
Subsequent Event [Member] | New Credit Agreement Revolving Line of Credit [Member] | Maximum [Member]
Facilities, unused capacity, commitment fee percentage	0.45%
Subsequent Event [Member] | New Credit Agreement [Member]
Facilities, maximum borrowing capacity	$ 400,000,000
Facilities, amount outstanding	$ 247,000,000
Facilities, maturity date	Nov. 12, 2021
Subsequent Event [Member] | New Credit Agreement [Member] | Maximum [Member]
Total leverage ratio	3
Subsequent Event [Member] | New Credit Agreement [Member] | Base Rate [Member]
Description of variable rate basis	the highest of (a) the prime rate of the administrative agent, (b) ½ of 1% above the federal funds effective rate published by the Federal Reserve Bank of New York and (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1.00%.
Basis spread on variable rate	2.00%
Subsequent Event [Member] | New Credit Agreement [Member] | Base Rate [Member] | Minimum [Member]
Basis spread on variable rate	0.25%
Subsequent Event [Member] | New Credit Agreement [Member] | Base Rate [Member] | Maximum [Member]
Basis spread on variable rate	1.25%
Subsequent Event [Member] | New Credit Agreement [Member] | LIBOR [Member]
Basis spread on variable rate	1.00%
Subsequent Event [Member] | New Credit Agreement [Member] | LIBOR [Member] | Minimum [Member]
Basis spread on variable rate	1.25%
Subsequent Event [Member] | New Credit Agreement [Member] | LIBOR [Member] | Maximum [Member]
Basis spread on variable rate	2.25%
Subsequent Event [Member] | New Credit Agreement [Member] | Federal Funds [Member]
Basis spread on variable rate	1.00%
Subsequent Event [Member] | United States of America, Dollars | New Credit Agreement [Member]
Description of variable rate basis	(1) the New Base Rate (as defined below) plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) LIBOR (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio (such margin, the “New Applicable Margin”).

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	9 Months Ended
	Oct. 30, 2016	Jan. 31, 2016
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	35.00%
Percentage of uncertain tax positions evaluating criteria	50.00%
Gross unrecognized tax benefit before federal impact of state items	$ 10,600,000	$ 10,600,000
Net tax benefits, if recognized, would impact the effective tax rate	8,400,000	8,400,000
Unrecognized tax benefits, interest and penalties	$ 293,000	$ 293,000

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Contingencies (Details) $ in Thousands	9 Months Ended
	Oct. 30, 2016USD ($)
Income Tax Contingency [Line Items]
Beginning balance	$ 8,432
Additions based on tax positions related to the current year	80
Reductions for tax positions of prior years, net	(121)
Reductions for settlements with tax authorities	0
Ending balance	$ 8,391

Income Taxes - Liability For Un

Income Taxes - Liability For Uncertain Tax Positions (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016
Income Tax Contingency [Line Items]
Liability for UTP	$ 8,391	$ 8,432
Non-current deferred tax asset [Member]
Income Tax Contingency [Line Items]
Liability for UTP	7,121	7,162
Other liabilities [Member]
Income Tax Contingency [Line Items]
Liability for UTP	$ 1,270	$ 1,270

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016	Mar. 04, 2015
Commitments and Contingencies [Line Items]
Potential payments under earn-out arrangements, high estimate			$ 70,000
Earn-out liability booked	$ 8,264	$ 6,259
Amount expected to be settled within twelve months	1,829	2,155
Cycleo [Member]
Commitments and Contingencies [Line Items]
Potential payments under earn-out arrangements, high estimate	16,000
Earn-out liability booked	8,264	6,259
Amount expected to be settled within twelve months	1,829	2,155
Triune Systems [Member]
Commitments and Contingencies [Line Items]
Earn-out liability booked	0	0	16,200
Amount expected to be settled within twelve months	0	$ 0
Additional Earn-out Payable After Third Fiscal Year From Acquisition Date [Member] | Triune Systems [Member]
Commitments and Contingencies [Line Items]
Potential payments under earn-out arrangements, high estimate			$ 16,000
Minimum [Member] | Environmental Issue
Commitments and Contingencies [Line Items]
Loss contingency, estimate of possible loss	5,200
Maximum [Member] | Environmental Issue
Commitments and Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 7,500

Commitments and Contingencies76

Commitments and Contingencies - Summary of Accrual for Environmental Loss Contingencies (Details) $ in Thousands	9 Months Ended
	Oct. 30, 2016USD ($)
Site Contingency [Line Items]
Beginning balance	$ 5,330
Change in estimate	0
Utililzation	(116)
Ending balance	5,214
Accrued Liabilities [Member]
Site Contingency [Line Items]
Beginning balance	1,150
Change in estimate	(499)
Utililzation	(116)
Ending balance	535
Other Long-term Liabilities [Member]
Site Contingency [Line Items]
Beginning balance	4,180
Change in estimate	499
Utililzation	0
Ending balance	$ 4,679

Commitments and Contingencies77

Commitments and Contingencies - Summary of Earn-out Liability (Details) - USD ($) $ in Thousands	Oct. 30, 2016	Jan. 31, 2016	Mar. 04, 2015
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	$ 8,264	$ 6,259
Amount expected to be settled within twelve months	1,829	2,155
Compensation Expense [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	6,379	4,397
Not Conditional Upon Continued Employment [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	1,295	1,457
Interest Expense [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	590	405
Triune Systems [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	0	0	$ 16,200
Amount expected to be settled within twelve months	0	0
Triune Systems [Member] | Compensation Expense [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	0	0
Triune Systems [Member] | Not Conditional Upon Continued Employment [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	0	0
Triune Systems [Member] | Interest Expense [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	0	0
Cycleo [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	8,264	6,259
Amount expected to be settled within twelve months	1,829	2,155
Cycleo [Member] | Compensation Expense [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	6,379	4,397
Cycleo [Member] | Not Conditional Upon Continued Employment [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	1,295	1,457
Cycleo [Member] | Interest Expense [Member]
Business Acquisition, Contingent Consideration [Line Items]
Earn-out liability booked	$ 590	$ 405

Concentration of Risk - Narrati

Concentration of Risk - Narrative (Details)	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Concentration Risk [Line Items]
Description of geographic concentration risk related to distributors	For the third quarter of fiscal year 2017, our two largest distributors were based in Asia.
Sales Revenue, Goods, Net [Member]
Concentration Risk [Line Items]
Minimum concentration risk threshold	10.00%
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Accounts Receivable [Member]
Concentration Risk [Line Items]
Minimum concentration risk threshold	10.00%
Net sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Net sales [Member] | Distributor concentration risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	64.00%	56.00%
China | Cost of Silicon Wafers [Member] | Supplier concentration risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	24.00%	29.00%

Concentration of Risk - Schedul

Concentration of Risk - Schedule Of Significant Customers Accounting For At Least 10% Of Net Sales During Period (Details) - Sales Revenue, Goods, Net [Member]	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Concentration Risk [Line Items]
Minimum concentration risk threshold	10.00%
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Customer Concentration Risk [Member] | Arrow (and affiliates) [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	10.00%	9.00%	9.00%

Segment Information - Narrative

Segment Information - Narrative (Details)	3 Months Ended	6 Months Ended	9 Months Ended
	Oct. 30, 2016operating_segment	Jul. 31, 2016operating_segment	Oct. 30, 2016reportable_segment
Segment Reporting [Abstract]
Number of operating segments | operating_segment	4	5
Number of operating segments that aggregate into one reportable segment			4
Number of reportable segments			1

Segment Information - Net Sales

Segment Information - Net Sales Activity by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Revenue from External Customer [Line Items]
Net sales	$ 137,185	$ 115,810	$ 404,241	$ 371,610
Semiconductor Products Group [Member]
Revenue from External Customer [Line Items]
Net sales	137,185	115,795	404,036	369,690
All others [Member]
Revenue from External Customer [Line Items]
Net sales	$ 0	$ 15	$ 205	$ 1,920

Segment Information - Income (L

Segment Information - Income (Loss) by Segment and Reconciliation to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Segment Reporting Information [Line Items]
Operating income (loss)	$ 39,099	$ 18,898	$ 68,794	$ 26,850
Items to reconcile segment operating income to consolidated income before taxes
Share-based compensation	9,395	5,117	21,198	13,397
Changes in the fair value of contingent earn-out obligations	0	(14,186)	(162)	(13,618)
Restructuring charge	0	962	0	4,526
Interest expense, net	1,890	1,964	5,857	5,698
Non-operating expense, net	690	777	871	1,152
Income before taxes	36,519	16,157	62,066	20,000
Corporate, Non-Segment [Member]
Items to reconcile segment operating income to consolidated income before taxes
Intangible amortization and impairments	6,286	6,308	19,017	18,648
Share-based compensation	9,395	5,117	21,199	13,397
Changes in the fair value of contingent earn-out obligations	0	(14,186)	(162)	(13,618)
Restructuring charge	0	962	0	4,526
Environmental reserve	0	0	0	2,855
Other non-segment related (income) expenses	3,139	2,792	5,938	10,073
Amortization of fair value adjustments related to acquired PP&E	308	310	925	948
Interest expense, net	1,890	1,964	5,857	5,698
Non-operating expense, net	690	777	871	1,152
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	58,227	20,201	115,711	63,679
Semiconductor Products Group [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	33,013	22,019	92,973	70,054
All others [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	$ 25,214	$ (1,818)	$ 22,738	$ (6,375)

Segment Information - Revenue b

Segment Information - Revenue by Product Line (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Revenue from External Customer [Line Items]
Net sales	$ 137,185,000	$ 115,810,000	$ 404,241,000	$ 371,610,000
Signal Integrity [Member]
Revenue from External Customer [Line Items]
Net sales	60,550,000	52,449,000	193,745,000	165,780,000
Protection [Member]
Revenue from External Customer [Line Items]
Net sales	40,250,000	33,225,000	108,296,000	105,339,000
Wireless and Sensing [Member]
Revenue from External Customer [Line Items]
Net sales	24,070,000	16,567,000	60,514,000	54,898,000
Power and High Reliability [Member]
Revenue from External Customer [Line Items]
Net sales	15,984,000	13,554,000	45,150,000	43,673,000
Systems Innovation [Member]
Revenue from External Customer [Line Items]
Net sales	0	15,000	205,000	1,920,000
Other: Warrant Shares [Member]
Revenue from External Customer [Line Items]
Net sales offset	$ (3,669,000)	$ 0	$ (3,669,000)	$ 0
Net sales [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Net sales [Member] | Signal Integrity [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	44.00%	45.00%	48.00%	44.00%
Net sales [Member] | Protection [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	29.00%	29.00%	27.00%	28.00%
Net sales [Member] | Wireless and Sensing [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	18.00%	14.00%	15.00%	15.00%
Net sales [Member] | Power and High Reliability [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	12.00%	12.00%	11.00%	12.00%
Net sales [Member] | Systems Innovation [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	0.00%	0.00%	0.00%	1.00%
Net sales [Member] | Other: Warrant Shares [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	(3.00%)	0.00%	(1.00%)	0.00%

Segment Information - Net Sal84

Segment Information - Net Sales Activity by Geographic Region (Details) - Sales Revenue, Goods, Net [Member]	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	80.00%	70.00%	79.00%	72.00%
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	16.00%	20.00%	16.00%	18.00%
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	7.00%	10.00%	8.00%	10.00%
Other: Warrant Shares [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	(3.00%)	0.00%	(3.00%)	0.00%

Segment Information - Summary o

Segment Information - Summary of Sales Activity to Countries that Represented Greater than 10% of Total Net Sales (Details) - Sales Revenue, Goods, Net [Member]	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Minimum concentration risk threshold	10.00%
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Other: Warrant Shares [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	(3.00%)	0.00%	(3.00%)	0.00%
Geographic Concentration Risk [Member] | China Including Hong Kong [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	46.00%	45.00%	45.00%	44.00%
Geographic Concentration Risk [Member] | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	11.00%	14.00%	11.00%	12.00%
Geographic Concentration Risk [Member] | Other: Warrant Shares [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	(3.00%)	0.00%	(3.00%)	0.00%

Segment Information - Income 86

Segment Information - Income (Loss) from Continuing Operations Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	$ 36,519	$ 16,157	$ 62,066	$ 20,000
Domestic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	937	21,146	(13,048)	3,785
Canada
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	31,385	2,440	49,302	16,494
United Kingdom
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	3,568	4,984	14,150	17,328
Switzerland
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	764	(13,411)	7,791	(5,063)
Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	344	1,424	2,470	2,486
Other Foreign [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) before taxes	$ (479)	$ (426)	$ 1,401	$ (15,030)

Stock Repurchase Program - Narr

Stock Repurchase Program - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		103 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016
Equity [Abstract]
Repurchased shares of common stock, cost	$ 0	$ 7,464	$ 538	$ 57,311	$ 136,200
Remaining authorization under stock repurchase program	$ 62,200		$ 62,200		$ 62,200

Stock Repurchase Program - Summ

Stock Repurchase Program - Summary of Stock Repurchases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		103 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016
Equity [Abstract]
Repurchase Program expenditures, shares	0	491,316	23,968	2,681,476
Repurchase Program expenditures, value	$ 0	$ 7,464	$ 538	$ 57,311	$ 136,200

Divestitures - Narrative (Detai

Divestitures - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015	Aug. 05, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of business operations	$ 25,036	$ 0	$ 25,036	$ 0
Defense And Microwave Communications Infrastructure Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues and NRE reimbursements		$ 200		$ 4,300
Noncash divestiture, description		Under the terms of the transaction with Jariet, the Company contributed assets, including inventory and equipment with a net book value of $0.6 million in exchange for an equity interest in the form of preferred stock, representing an approximately 21% voting interest in Jariet. Due to the anticipated continuing cash flows from its investment in Jariet, the Company did not account for the divestiture as a discontinued operation. In addition to the contribution of assets, certain contracts were novated with future performance responsibilities being transferred to Jariet. The investment in Jariet was written off in the third quarter of fiscal year 2016.
Net book value of contributed assets		$ 600
Type of consideration received		equity interest in the form of preferred stock
Voting interest acquired		21.00%
Systems Innovation [Member] | Snowbush IP Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration received related to divestiture					$ 32,000
Gain on Disposition of Business Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of business operations	$ 25,036

Restructuring Activity (Details

Restructuring Activity (Details) - One-time Termination Benefits [Member] $ in Thousands	9 Months Ended
	Oct. 30, 2016USD ($)
Restructuring Cost and Reserve [Line Items]
Beginning balance	$ 342
Adjustments	0
Cash payments	(336)
Ending balance	$ 6

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	9 Months Ended
	Oct. 30, 2016USD ($)
Variable Interest Entity [Line Items]
Nature and extent of involvement in VIE	With regards to its investment in MultiPhy, the Company concluded that its equity interest represents a variable interest, but it is not the primary beneficiary as prescribed in ASC 810. Specifically, in reaching this conclusion, the Company considered the activities that most significantly drive profitability for MultiPhy and determined that the activity that most significantly drove profitability was related to the technology and related product road maps. The Company has a board observer role and thus concluded that it was not in a position of decision-making or other authority to influence MultiPhy’s activities that could be considered significant with respect to its operations, including research and development plans and changes to the product road map.
MultiPhy Ltd [Member]
Variable Interest Entity [Line Items]
Maximum exposure to loss as a result of investment	$ 14

Derivatives and Hedging Activ92

Derivatives and Hedging Activities - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Derivative [Line Items]
Objectives for using derivative instruments			The Company is exposed to certain risk arising from both its business operations and economic conditions and principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company, on a routine basis and in the normal course of business, experiences expenses denominated in Swiss Franc (“CHF”), Canadian Dollar (“CAD”) and Great British Pound (“GBP”). Such expenses expose the Company to exchange rate fluctuations between these foreign currencies and the U.S. Dollar (“USD”). The Company uses derivative financial instruments in the form of forward contracts, to mitigate risk associated with adverse movements in these foreign currency exchange rates on a portion of foreign denominated expenses expected to be realized during the current and following fiscal year.
Other comprehensive (income) loss, net of tax	$ 3,847	$ (129)	$ 3,477	$ (266)
Foreign Contract
Derivative [Line Items]
Other comprehensive (income) loss, net of tax			$ 225	$ 0

Derivatives and Hedging Activ93

Derivatives and Hedging Activities - Summary of Open Foreign Currency Contracts (Details) £ in Thousands, SFr in Thousands, CAD in Thousands, $ in Thousands	Oct. 30, 2016USD ($)	Oct. 30, 2016GBP (£)	Oct. 30, 2016CAD	Oct. 30, 2016CHF (SFr)
Derivative [Line Items]
Number of Instruments	21	21	21	21
Sell USD/Buy CHF Forward Contract [Member]
Derivative [Line Items]
Number of Instruments	3	3	3	3
Sell USD/Buy CAD Forward Contract [Member]
Derivative [Line Items]
Number of Instruments	3	3	3	3
Sell USD/Buy GBP Forward Contract [Member]
Derivative [Line Items]
Number of Instruments	15	15	15	15
Short [Member] | Sell USD/Buy CHF Forward Contract [Member]
Derivative [Line Items]
Notional Value	$ 2,732
Short [Member] | Sell USD/Buy CAD Forward Contract [Member]
Derivative [Line Items]
Notional Value	4,532
Short [Member] | Sell USD/Buy GBP Forward Contract [Member]
Derivative [Line Items]
Notional Value	$ 13,568
Long [Member] | Sell USD/Buy CHF Forward Contract [Member]
Derivative [Line Items]
Notional Value | SFr				SFr 2,672
Long [Member] | Sell USD/Buy CAD Forward Contract [Member]
Derivative [Line Items]
Notional Value | CAD			CAD 6,337
Long [Member] | Sell USD/Buy GBP Forward Contract [Member]
Derivative [Line Items]
Notional Value | £		£ 10,744

Derivatives and Hedging Activ94

Derivatives and Hedging Activities - Summary of the Carrying Values of Derivative Instruments (Details) - USD ($) $ in Thousands		Oct. 30, 2016	Jan. 31, 2016
Derivatives, Fair Value [Line Items]
Fair Value - Assets		$ 215	$ 0
Fair Value - (Liabilities)		(445)	0
Derivative Net Carrying Value		(230)	0
Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Net Carrying Value	[1]	(230)	0
Level 2 [Member] | Foreign Exchange Contract [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair Value - Assets	[1],[2]	215	0
Level 2 [Member] | Foreign Exchange Contract [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair Value - (Liabilities)	[1],[2]	$ (445)	$ 0
[1]	Assets are included in “Other current assets” and liabilities are included in “Accrued liabilities” within the condensed consolidated balance sheets.
[2]	The fair values of the foreign exchange forward contracts are valued using Level 2 inputs. Please refer to Note 7.

Derivatives and Hedging Activ95

Derivatives and Hedging Activities - Summary of Gain (Loss) Recognized From Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in AOCI on derivative (effective portion)			$ 321
Amount of loss recognized in AOCI on derivative (effective portion)	$ (422)
Amount of (gain) loss reclassified from AOCI into income (effective portion)	(88)	$ 0	(546)	$ 0
SG&A
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss reclassified from AOCI into income (effective portion)	(88)	0	(546)	0
Amount of gain (loss) recognized into income on derivative (ineffective portion and amount excluded from effectiveness testing)	(3)	0	2	0
Sell USD/Buy CHF Forward Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in AOCI on derivative (effective portion)			51
Amount of loss recognized in AOCI on derivative (effective portion)	(85)
Sell USD/Buy CHF Forward Contract [Member] | SG&A
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss reclassified from AOCI into income (effective portion)	(24)	0	(72)	0
Amount of gain (loss) recognized into income on derivative (ineffective portion and amount excluded from effectiveness testing)	(1)	0	0	0
Sell USD/Buy CAD Forward Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in AOCI on derivative (effective portion)			1,113
Amount of loss recognized in AOCI on derivative (effective portion)	(141)
Sell USD/Buy CAD Forward Contract [Member] | SG&A
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss reclassified from AOCI into income (effective portion)	(334)	0	(909)	0
Amount of gain (loss) recognized into income on derivative (ineffective portion and amount excluded from effectiveness testing)	0	0	5	0
Sell USD/Buy GBP Forward Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in AOCI on derivative (effective portion)	(196)		(843)
Sell USD/Buy GBP Forward Contract [Member] | SG&A
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss reclassified from AOCI into income (effective portion)	270	0	435	0
Amount of gain (loss) recognized into income on derivative (ineffective portion and amount excluded from effectiveness testing)	$ (2)	$ 0	$ (3)	$ 0

Subsequent Events (Details)

Subsequent Events (Details)	Nov. 15, 2016USD ($)	May 02, 2013USD ($)	Oct. 30, 2016
Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity		$ 400,000,000
New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	$ 400,000,000
Facilities, maturity date	Nov. 12, 2021
Facilities, amount outstanding	$ 247,000,000
Minimum percentage of lenders as represented by revolving commitments and outstanding term loans	50.00%
New Credit Agreement Term Loans [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	$ 150,000,000
Facilities, amount outstanding	$ 150,000,000
Debt, payment terms	The outstanding principal balance of the term loans will be subject to repayment in quarterly installments beginning on the last day of Semtech’s fiscal quarter ending closest to January 31, 2017 in an amount equal to $3,750,000 per quarter for the first two years after the Closing Date, $4,697,500 per quarter in the third and fourth years following the Closing Date, and $5,625,000 per quarter in the fifth year following the Closing Date, with the balance being due at maturity on November 12, 2021.
Percentage of long-term debt subject to repayment in years one and two	10.00%
Percentage of long-term debt subject to repayment in years three and four	12.50%
Percentage of long-term debt subject to repayment in year five	15.00%
New Credit Agreement Revolving Line of Credit [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	$ 250,000,000
Facilities, amount outstanding	$ 97,000,000
Facilities, unused capacity, commitment fee percentage	0.40%
New Credit Agreement Letter of Credit [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	$ 40,000,000
Facilities, amount outstanding
Fronting fee percentage for each letter of credit issued	0.125%
New Credit Agreement Swingline Loans [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	$ 25,000,000
Facilities, amount outstanding
Facilities, balance undrawn	153,000,000
New Credit Agreement Foreign Line of Credit [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	40,000,000
Facilities, amount outstanding
New Credit Agreement Additional Term Loan or Increase in Revolver [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, maximum borrowing capacity	$ 150,000,000
Federal Funds [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Basis spread on variable rate		1.00%
Federal Funds [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	1.00%
Base Rate [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Description of variable rate basis		the highest of (a) the prime rate (as published by The Wall Street Journal), (b) ½ of 1% above the federal funds effective rate or (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1%.
Base Rate [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Description of variable rate basis	the highest of (a) the prime rate of the administrative agent, (b) ½ of 1% above the federal funds effective rate published by the Federal Reserve Bank of New York and (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1.00%.
Basis spread on variable rate	2.00%
LIBOR [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Basis spread on variable rate		1.00%
LIBOR [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	1.00%
Minimum [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum leverage ratio following a material acquisition	3.25
Minimum [Member] | New Credit Agreement Revolving Line of Credit [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, unused capacity, commitment fee percentage	0.20%
Minimum [Member] | Base Rate [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Basis spread on variable rate		0.25%
Minimum [Member] | Base Rate [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	0.25%
Minimum [Member] | LIBOR [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Basis spread on variable rate		1.25%
Minimum [Member] | LIBOR [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	1.25%
Maximum [Member]
Subsequent Event [Line Items]
Total leverage ratio			3
Maximum [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Total leverage ratio	3
Maximum leverage ratio following a material acquisition	3.50
Maximum [Member] | New Credit Agreement Revolving Line of Credit [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Facilities, unused capacity, commitment fee percentage	0.45%
Maximum [Member] | Base Rate [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Basis spread on variable rate		1.25%
Maximum [Member] | Base Rate [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	1.25%
Maximum [Member] | LIBOR [Member] | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Basis spread on variable rate		2.25%
Maximum [Member] | LIBOR [Member] | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Basis spread on variable rate	2.25%
United States of America, Dollars | Prior Credit Agreement [Member]
Subsequent Event [Line Items]
Description of variable rate basis		(1) the Base Rate plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) LIBOR (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio.
United States of America, Dollars | New Credit Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Description of variable rate basis	(1) the New Base Rate (as defined below) plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) LIBOR (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio (such margin, the “New Applicable Margin”).