AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MARCH 19, 1999
    
 
                                                      REGISTRATION NO. 333-69469
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                           --------------------------
 
   
                                AMENDMENT NO. 2
                                       TO
                                    FORM S-3
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
    
 
                           --------------------------
 
                       LATTICE SEMICONDUCTOR CORPORATION
             (Exact name of registrant as specified in its charter)
 
                           --------------------------
 

                                                   
                      DELAWARE                                             93-0835214
          (State or other jurisdiction of                               (I.R.S. Employer
           incorporation or organization)                            Identification Number)

 
   
                             5555 N.E. MOORE COURT
                          HILLSBORO, OREGON 97124-6421
                                 (503) 268-8000
  (Address, including zip code, and telephone number, including area code, of
                   Registrant's principal executive offices)
    
 
                           --------------------------
 
   
                               STEPHEN A. SKAGGS
                            CHIEF FINANCIAL OFFICER
                       LATTICE SEMICONDUCTOR CORPORATION
                             5555 N.E. MOORE COURT
                          HILLSBORO, OREGON 97124-6421
                                 (503) 268-8000
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)
    
 
                           --------------------------
 
                                    COPY TO:
 
                               JOHN A. FORE, ESQ.
                        WILSON SONSINI GOODRICH & ROSATI
                            PROFESSIONAL CORPORATION
                               650 PAGE MILL ROAD
                              PALO ALTO, CA 94304
                                 (650) 493-9300
 
                           --------------------------
 
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
As soon as practicable after the effective date of this Registration Statement.
 
                           --------------------------
 
    If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. / /
 
    If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. /X/
 
    If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /
 
    If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /
 
   
    If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /
    
 
                           --------------------------
 
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a),
MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY
NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER
TO SELL THESE SECURITIES AND IT IS NOT SOLICITING AN OFFER TO BUY THESE
SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

   
                  SUBJECT TO COMPLETION, DATED MARCH 19, 1999
    
 
                             PRELIMINARY PROSPECTUS
 
                                     [LOGO]
 
                                 50,098 SHARES
 
                                  COMMON STOCK
 
                                ---------------
 
   
        This prospectus relates to 50,098 shares of common stock, $0.01 par
    value, of Lattice Semiconductor Corporation that are issuable upon
    exercise of a warrant granted to Bain & Company, Inc., the selling
    stockholder identified in this prospectus. The selling stockholder is
    offering all of the shares to be sold in the offering. Lattice will not
    receive any of the proceeds from the offering.
    
 
        Lattice's common stock is traded on the Nasdaq National Market under
    the symbol "LSCC."
 
                        --------------------------------
 
   
        See "Risk Factors" on page 2 for information you should consider
    before buying the securities.
    
 
                        --------------------------------
 
        NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE
    SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR
    DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY
    REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
                        --------------------------------
 
                   The date of this prospectus is

   
                                  RISK FACTORS
    
 
    AN INVESTMENT IN THE SHARES OF OUR COMMON STOCK OFFERED BY THIS PROSPECTUS
INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD CAREFULLY REVIEW THE FOLLOWING RISK
FACTORS AS WELL AS THE OTHER INFORMATION IN THIS PROSPECTUS BEFORE MAKING AN
INVESTMENT.
 
   
    SOME OF THE INFORMATION IN THIS PROSPECTUS CONTAINS FORWARD-LOOKING
STATEMENTS THAT INVOLVE SUBSTANTIAL RISKS AND UNCERTAINTIES. YOU CAN IDENTIFY
THESE STATEMENTS BY FORWARD-LOOKING WORDS SUCH AS "MAY," "WILL," "EXPECT,"
"ANTICIPATE," "BELIEVE," "ESTIMATE" AND "CONTINUE" OR SIMILAR WORDS.
    
 
   
    YOU SHOULD READ STATEMENTS THAT CONTAIN THESE WORDS CAREFULLY BECAUSE THEY:
    
 
   
    - DISCUSS OUR FUTURE EXPECTATIONS;
    
 
   
    - PROJECT OUR FUTURE OPERATING RESULTS OR FINANCIAL CONDITION; OR
    
 
   
    - STATE OTHER "FORWARD-LOOKING" INFORMATION.
    
 
   
    WE BELIEVE IT IS IMPORTANT TO COMMUNICATE OUR EXPECTATIONS TO OUR INVESTORS.
THERE MAY BE EVENTS IN THE FUTURE, HOWEVER, THAT WE ARE NOT ACCURATELY ABLE TO
PREDICT OR OVER WHICH WE HAVE NO CONTROL.
    
 
   
    THE RISK FACTORS LISTED IN THIS SECTION, AS WELL AS ANY CAUTIONARY LANGUAGE
IN THIS PROSPECTUS, PROVIDE EXAMPLES OF RISKS, UNCERTAINTIES AND EVENTS THAT MAY
CAUSE OUR ACTUAL RESULTS TO DIFFER MATERIALLY FROM THE EXPECTATIONS WE DESCRIBE
IN OUR FORWARD-LOOKING STATEMENTS. BEFORE YOU INVEST IN OUR COMMON STOCK, YOU
SHOULD BE AWARE THAT THE OCCURRENCE OF ANY OF THE EVENTS DESCRIBED IN THESE RISK
FACTORS AND ELSEWHERE IN THIS PROSPECTUS COULD HAVE A MATERIAL ADVERSE EFFECT ON
OUR BUSINESS, FINANCIAL CONDITION AND OPERATING RESULTS. ADDITIONALLY, UPON THE
OCCURRENCE OF ANY OF THESE EVENTS, THE TRADING PRICE OF OUR COMMON STOCK COULD
DECLINE AND YOU COULD LOSE ALL OR PART OF YOUR INVESTMENT.
    
 
   
AN INTERRUPTION OR SHORTAGE OF OUR FINISHED SILICON WAFER SUPPLY WOULD HAVE AN
  ADVERSE EFFECT ON OUR BUSINESS.
    
 
   
    We do not manufacture finished silicon wafers. However, our semiconductor
products require silicon wafers manufactured with state-of-the-art fabrication
equipment and techniques. As a result, our strategy has been to maintain
relationships with semiconductor foundries for our silicon wafer production. All
our silicon wafers are currently manufactured by either Seiko Epson in Japan or
the UMC Group, a group of affiliated companies in Taiwan. If Seiko Epson,
through its U.S. affiliate Epson Electronics America, or the UMC Group
significantly interrupts our wafer supply, our operating results would be
adversely affected.
    
 
   
    Since worldwide manufacturing capacity for silicon wafers is limited and
inelastic, we could be adversely affected by significant industry wide increases
in overall wafer demand or interruptions in wafer supply. In the past, we have
experienced delays in obtaining wafers and supply commitments from our
foundries. We negotiate wafer prices and supply commitments on at least an
annual basis with Seiko Epson, Epson Electronics America and the UMC Group. We
anticipate that our current supply commitments are adequate through fiscal 1999.
However, existing supply commitments may not be sufficient for us to satisfy
customer demand in future periods. If Seiko Epson, Epson Electronics America or
the UMC Group reduces our supply commitment or increases our wafer prices, and
we cannot find alternative sources of wafer supply, our operating results could
be adversely affected.
    
 
    Many of the other factors that could change or disrupt our wafer supply
arrangements are beyond our control. For example, a disruption of Seiko Epson's
or UMC Group's foundry operations as a result of a fire, earthquake or other
natural disaster would disrupt our wafer shipments and would have an adverse
effect on our operating results.
 
                                       2

   
OUR BUSINESS COULD BE ADVERSELY AFFECTED IF SILICON WAFER QUALITY AND YIELD
  LEVELS ACHIEVED BY OUR FOUNDRY PARTNERS DETERIORATE.
    
 
   
    We depend on our foundries to produce and deliver silicon wafers with
acceptable yields in a timely manner. Substantially all of our revenues are
derived from semiconductor products based on a specialized silicon wafer
manufacturing process technology called E(2)CMOS-Registered Trademark-. The
reliable manufacture of high performance E(2)CMOS semiconductors is a
complicated and technically demanding process. In order to produce acceptable
yields, this manufacturing process requires:
    
 
    - a high degree of technical skill;
 
    - state-of-the-art equipment;
 
    - the absence of defects in the masks used to print circuits on a wafer;
 
    - the elimination of minute impurities and errors in each step of the
      fabrication process; and
 
    - effective cooperation between the wafer supplier and the circuit designer.
 
   
    As is common in our industry, we have experienced yield problems and
delivery delays in the past. If our foundries are unable to produce silicon
wafers that meet our specifications with acceptable yields, for a prolonged
period, our operating results could be adversely affected.
    
 
   
OUR BUSINESS COULD BE ADVERSELY AFFECTED IF WE ARE NOT SUCCESSFUL IN MIGRATING
  OUR SILICON WAFER PRODUCTION PROCESSES TO MORE ADVANCED TECHNOLOGIES.
    
 
   
    Our future success will depend in part on our ability to maintain and
enhance our wafer manufacturing process technology. We anticipate in the future
migrating to more advanced wafer manufacturing process technologies using larger
wafer sizes and smaller device geometries. We may also utilize additional
foundries. Since we depend upon our foundries to provide their facilities and
support for our process technology development, we may experience delays in the
availability of advanced wafer manufacturing process technologies at existing or
new wafer fabrication facilities. As a result, volume production of our
E(2)CMOS-Registered Trademark- process technology at the new fabs of Seiko
Epson, the UMC Group or another foundry may not be achieved. This could have an
adverse effect on our operating results.
    
 
   
IF WE ARE NOT SUCCESSFUL IN DEFINING, DEVELOPING OR SELLING NEW PRODUCTS, OUR
  FINANCIAL PERFORMANCE WILL BE ADVERSELY AFFECTED.
    
 
   
    As with many semiconductor companies, which frequently operate in a highly
competitive, dynamic environment marked by rapid product obsolescence, our
future success depends on our ability to introduce new or improved products that
meet the needs of customers in a timely fashion while achieving acceptable
margins. Our future revenue growth depends on the market acceptance of our new
proprietary ISP-TM- product families and the continued market acceptance of our
proprietary software development tools. The success of these products will
depend on a variety of factors including:
    
 
    - product definition;
 
    - timely and efficient completion of product design;
 
    - timely and efficient implementation of wafer manufacturing and assembly
      processes;
 
    - product performance;
 
    - the quality and reliability of the product; and
 
    - effective sales and marketing.
 
                                       3

   
    For us, and many other semiconductor companies, the introduction of new
products in an increasingly complex environment presents significant challenges.
For example, our product development commitments and expenditures must be made
well in advance of product sales. Therefore, the success of new or improved
products depends on our ability to accurately forecast long-term market demand
and future technology developments. Even if we accurately forecast long-term
market demand and future technology developments, competitors may introduce
alternative products that could adversely affect the market acceptance of our
new or improved products. If these product development efforts are not
successful or these products do not achieve market acceptance, our operating
results will be adversely affected.
    
 
   
CONTINUED DETERIORATION OF CONDITIONS IN ASIA MAY DISRUPT OUR EXISTING SUPPLY
  ARRANGEMENTS AND COULD HAVE AN ADVERSE EFFECT ON OUR OPERATING RESULTS.
    
 
   
    Our two silicon wafer suppliers operate fabs in Asia. Our finished silicon
wafers are assembled and tested by independent subcontractors located in Hong
Kong, Malaysia, the Philippines, South Korea and Taiwan. A prolonged
interruption in our supply from any of these subcontractors could have an
adverse effect on our operating results. Although we have yet not experienced
significant supply interruptions, the economic, financial, social and political
situation in Asia has recently been volatile. Financial difficulties,
governmental actions and restrictions, prolonged work stoppages or any other
difficulties experienced by these suppliers as a result of conditions in Asia
may disrupt our supply and could have an adverse effect on our operating
results.
    
 
   
    Our wafer purchases from Seiko Epson are denominated in Japanese yen. The
value of the dollar with respect to the yen has fluctuated in the past and may
not remain stable in the future. Future substantial deterioration of dollar-yen
exchange rates could have an adverse effect on our operating results.
    
 
   
OUR OPERATING RESULTS COULD BE NEGATIVELY AFFECTED BY SIGNIFICANT UNCERTAINTIES
  ASSOCIATED WITH EXPORT SALES TO FOREIGN COUNTRIES.
    
 
   
    Export sales accounted for 50% of our revenues for the first nine months of
fiscal 1999 and 51% of our revenues for the first nine months of fiscal 1998.
Our export sales are affected by unique risks frequently associated with foreign
economies including:
    
 
   
    - changes in local economic conditions;
    
 
   
    - exchange rate volatility;
    
 
   
    - the imposition of governmental controls;
    
 
   
    - export license requirements;
    
 
   
    - restrictions on the export of technology;
    
 
   
    - political instability;
    
 
   
    - trade restrictions;
    
 
   
    - changes in tax laws;
    
 
   
    - changes in tariffs or freight rates;
    
 
   
    - interruptions in air transportation; and
    
 
   
    - difficulties in staffing and managing foreign sales offices.
    
 
                                       4

   
    For example, our export sales have recently been affected by the Asian
economic crisis. Significant changes in the economic climate in the foreign
countries where we derive our export sales could have an adverse effect on our
operating results.
    
 
   
DETERIORATION IN THE QUALITY AND YIELD LEVELS ACHIEVED BY OUR ASSEMBLY AND TEST
  SUBCONTRACTORS COULD ADVERSELY AFFECT OUR BUSINESS.
    
 
   
    We rely on subcontractors to assemble and test our devices with acceptable
quality and yield levels. We have in the past experienced quality and yield
problems with our assembly and test subcontractors. The majority of our revenue
is derived from semiconductor products assembled in advanced packages. The
assembly of advanced packages is a complex process requiring:
    
 
    - a high degree of technical skill;
 
    - state-of-the-art equipment;
 
    - the absence of defects in lead frames used to attach semiconductor devices
      to the package;
 
    - the elimination of raw material impurities and errors in each step of the
      process; and
 
    - effective cooperation between the assembly subcontractor and the device
      manufacturer.
 
   
    If we experience prolonged quality or yield problems at our assembly and
test subcontractors in the future, there could be an adverse affect on our
operating results.
    
 
   
OUR FINANCIAL PERFORMANCE MAY BE NEGATIVELY IMPACTED BY A CYCLICAL DOWNTURN IN
  THE SEMICONDUCTOR INDUSTRY.
    
 
   
    The semiconductor industry is highly cyclical, to a greater extent than
other less dynamic or less technology-driven industries. In the past, our
financial performance has been negatively affected by significant downturns as a
result of:
    
 
    - diminished demand for semiconductor products;
 
    - general reductions in semiconductor inventory levels by customers;
 
    - excess production capacity; and
 
    - accelerated declines in average selling prices.
 
    If these or other conditions in the semiconductor industry occur in the
future, there could be an adverse effect on our operating results.
 
   
OUR FUTURE QUARTERLY OPERATING RESULTS MAY FLUCTUATE AND THEREFORE MAY FAIL TO
  MEET EXPECTATIONS.
    
 
   
    Our quarterly operating results have fluctuated in the past and may continue
to fluctuate in the future. Consequently, our operating results may fail to meet
expectations. As a result of industry conditions and the following specific
factors, our quarterly operating results are more likely to fluctuate and are
more difficult to predict than a typical non-technology company of our size and
maturity:
    
 
   
    - general economic conditions in the countries where we sell our products;
    
 
    - the timing of our and our competitors' new product introductions;
 
    - product obsolescence;
 
    - the scheduling, rescheduling and cancellation of large orders by our
      customers;
 
   
    - the cyclical nature of demand for our customers' products;
    
 
                                       5

    - our ability to develop new process technologies and achieve volume
      production at the new fabs of Seiko Epson, the UMC Group or another
      foundry;
 
    - changes in manufacturing yields;
 
    - adverse movements in exchange rates, interest rates or tax rates; and
 
    - the availability of adequate supply commitments from our wafer foundries
      and assembly and test subcontractors.
 
   
    As a result of these factors, our past financial results are not necessarily
a good predictor of our future financial results.
    
 
   
OUR STOCK PRICE MAY CONTINUE TO EXPERIENCE ABOVE AVERAGE VOLATILITY.
    
 
   
    In recent years, the price of our common stock has fluctuated greatly. The
price of our stock may continue to fluctuate greatly, due to a variety of
factors, including:
    
 
   
    - general price fluctuations of the overall stock market;
    
 
   
    - general price fluctuations of semiconductor stocks, reflecting in part the
      historical cyclicality of the semiconductor industry;
    
 
    - quarter to quarter variations in our operating results;
 
    - shortfalls in revenues or earnings from levels expected by securities
      analysts;
 
    - announcements of technological innovations or new products by us or our
      competitors; and
 
    - patent or other proprietary rights developments or litigation.
 
   
OUR FUTURE FINANCIAL RESULTS WOULD BE ADVERSELY AFFECTED IF WE ARE UNABLE TO
  COMPETE SUCCESSFULLY IN THE HIGHLY COMPETITIVE SEMICONDUCTOR INDUSTRY.
    
 
    The semiconductor industry is intensely competitive and is characterized by:
 
    - rapid technological change;
 
    - sudden price fluctuations;
 
    - price competition;
 
    - rapid rates of product obsolescence;
 
    - periodic shortages of materials and manufacturing capacity;
 
    - variations in manufacturing costs and yields; and
 
    - intense competition for sales and distribution channels.
 
    We compete with major domestic and international semiconductor companies as
well as with emerging companies. We compete directly with companies that have
developed or licensed similar technology and with companies that have licensed
our products and technology. We compete indirectly with a wide variety of
semiconductor companies that offer products and solutions based on alternative
technologies. In addition, we may experience significant competition from
foreign companies in the future. Many of our direct and indirect competitors
have substantially greater financial, technological, manufacturing, marketing
and sales resources than we do. Competition may also increase as the
programmable logic device market expands. If our competitors develop new
products or technologies with better price or performance characteristics, our
operating results could be adversely affected. In addition, if our products
become non-competitive or obsolete due to the introduction of competitive
products, our operating results could be adversely affected.
 
                                       6

   
OUR BUSINESS AND FINANCIAL PERFORMANCE COULD BE ADVERSELY AFFECTED IF WE ARE
  UNABLE TO ATTRACT AND RETAIN KEY TECHNICAL AND MANAGEMENT PERSONNEL REQUIRED
  FOR OUR BUSINESS.
    
 
   
    To a greater degree than most non-technology companies and larger companies,
our future success depends in part on our ability to attract and retain highly
qualified technical and management personnel, particularly highly skilled
engineers that can develop new products and process technologies. We compete for
these employees with other technology companies and government and academic
institutions. As a mid-size company, we are dependent on a small group of key
employees. Competition for these kinds of skilled technical and management
personnel is intense throughout our industry. As a result, we may not be able to
retain our existing key technical and management personnel. In addition, we may
not be able to attract additional qualified employees in the future. If we lose
existing qualified personnel or are unable to hire new qualified personnel, our
product development cycles could be delayed and our operating results could be
adversely affected.
    
 
   
WE MAY NOT BE ABLE TO ADEQUATELY PROTECT OUR INTELLECTUAL PROPERTY RIGHTS, AND
  MAY FACE SIGNIFICANT EXPENSE AS A RESULT OF FUTURE LITIGATION.
    
 
    Our success depends in part on our proprietary technology. We intend to
continue to protect our proprietary technology through patents, copyrights and
trade secrets. We believe that our future success will increasingly depend on:
 
    - technological expertise;
 
    - continued development of new and improved products; and
 
    - market acceptance of our new and improved silicon and software products.
 
However, we may not be able to protect our technology. In addition, our
competitors may develop similar technology independently. We currently have a
number of United States and foreign patents and patent applications. However,
the claims allowed on any of our patents may not be sufficiently broad to
protect our technology. We may also fail to obtain patents from pending and
filed patent applications. Finally, patents issued to us may be challenged,
invalidated or circumvented and any rights allowed under these patents may not
provide any competitive advantage.
 
    Companies in the semiconductor industry vigorously pursue protection of
their intellectual property rights. Any future protracted litigation we may be
involved in will utilize financial and management resources, which could have an
adverse effect on our operating results. We may also be subject to future
intellectual property claims. If these intellectual property claims were to
occur, we may not be able to obtain a license on favorable terms or without our
operating results being adversely affected.
 
   
WE MAY BE UNSUCCESSFUL IN ACHIEVING YEAR 2000 COMPLIANCE IN A TIMELY MANNER,
  WHICH COULD HAVE AN ADVERSE IMPACT ON OUR BUSINESS.
    
 
    Many currently installed computer systems and software products experience
difficulty distinguishing between twenty-first century dates and twentieth
century dates. This is commonly known as the Year 2000 problem.
 
    We are currently working to address the potential impact of the Year 2000 on
the processing of information by our computerized systems, including interfaces
to our business partners. We have established a project team to manage Year 2000
activities. The project is divided into three phases: assessment, compliance and
testing. We are currently in the compliance phase. We plan to complete our
compliance and testing effort by the third calendar quarter of 1999.
 
    We do not anticipate that resolution of Year 2000 issues will have a
material adverse impact on our financial position or operating results. As a
result, we have not yet established formal contingency
 
                                       7

   
plans. However, if we or our critical business partners are not successful in
addressing Year 2000 issues before the end of calendar year 1999, our operating
results could be adversely affected.
    
 
    We believe the most reasonably likely worst case Year 2000 scenario is a
temporary disruption in supplier deliveries or customer shipments. If severe
disruptions in these two areas occur and are not corrected in a timely manner,
we may experience a revenue or profit shortfall in the first half of calendar
year 2000.
 
                                USE OF PROCEEDS
 
   
    The proceeds received by Lattice upon exercise of the warrant will be used
for general working capital purposes.
    
 
                          PRICE RANGE OF COMMON STOCK
 
   
    The following table sets forth the range of high and low sale prices of
Lattice's common stock for the indicated periods, as reported by the Nasdaq
National Market. On March 18, 1999, the last reported sale price of the common
stock on the Nasdaq National Market was $45 15/16 per share. As of March 18,
1999, Lattice had approximately 347 holders of record of the common stock.
    
 
   


                                                       HIGH          LOW
                                                     ---------    ---------
                                                            
Fiscal year ended March 29, 1997:
  First Quarter...................................    36 1/4       21 5/8
  Second Quarter..................................    31 1/2       19 3/4
  Third Quarter...................................    47           27 1/2
  Fourth Quarter..................................    54 7/8       39 3/4
 
Fiscal year ended March 28, 1998:
  First Quarter...................................    62 5/8       41 1/2
  Second Quarter..................................    74 1/2       54 7/8
  Third Quarter...................................    67 1/2       45
  Fourth Quarter..................................    57           39 3/4
 
Fiscal year ending April 3, 1999
  First Quarter...................................    54 5/8       25 5/8
  Second Quarter..................................    36 5/8       23 1/4
  Third Quarter...................................    46 1/2       18 7/8
  Fourth Quarter (through March 18, 1999).........    56 5/16      37 3/4

    
 
                                DIVIDEND POLICY
 
    Lattice has never declared or paid cash dividends on its common stock. The
Board of Directors currently intends to retain all earnings for use in Lattice's
business. Therefore, Lattice does not anticipate declaring or paying any cash
dividends on its common stock in the foreseeable future.
 
   
                              PLAN OF DISTRIBUTION
    
 
   
    The selling stockholder may sell all or a portion of the shares from time to
time on the Nasdaq National Market for its own accounts at prices prevailing in
the public market at the times of such sales. The selling stockholder may also
make private sales directly or through one or more brokers. These brokers may
act as agents or as principals. The selling stockholder will pay all sales
commissions and similar expenses related to the sale of the shares. Lattice will
pay all expenses related to the registration of the shares.
    
 
                                       8

    The selling stockholder and any broker executing selling orders on behalf of
the selling stockholder may be considered an "underwriter" under the Securities
Act. As a result, commissions received by a broker may be treated as
underwriting commissions under the Securities Act. Any broker-dealer
participating as an agent in that kind of transaction may receive commissions
from the selling stockholder and from any purchaser of shares.
 
   
                       OFFICES AND PLACE OF INCORPORATION
    
 
   
    Lattice was incorporated in Oregon in 1983 and reincorporated in Delaware in
1985. Its principal executive offices are located at 5555 N.E. Moore Court,
Hillsboro, Oregon 97124-6421, and its telephone number at that location is (503)
268-8000.
    
 
                                 LEGAL MATTERS
 
    Wilson Sonsini Goodrich & Rosati, Professional Corporation, Palo Alto,
California, has passed upon the validity of the issuance of the common stock
offered by this prospectus for Lattice. Larry W. Sonsini, an officer of Wilson
Sonsini Goodrich & Rosati, Professional Corporation, is a director of Lattice
and owns options to purchase an aggregate of 18,000 shares of Lattice's common
stock and an aggregate of 2,340 shares of Lattice's common stock.
 
                                    EXPERTS
 
    The consolidated financial statements incorporated in this prospectus by
reference to the Annual Report on Form 10-K of Lattice Semiconductor Corporation
for the year ended March 28, 1998 have been so incorporated in reliance on the
report of PricewaterhouseCoopers LLP, independent accountants, given on the
authority of said firm as experts in auditing and accounting.
 
                      WHERE YOU CAN FIND MORE INFORMATION
 
    We file reports, proxy statements and other information with the Commission,
in accordance with the Securities and Exchange Act of 1934. You may read and
copy our reports, proxy statements and other information filed by us at the
public reference facilities of the Commission in Washington, D.C., New York, New
York, and Chicago, Illinois. Please call the Commission at 1-800-SEC-0330 for
further information about the public reference rooms. Our reports, proxy
statements and other information filed with the Commission are available to the
public over the Internet at the Commission's World Wide Web site
http://www.sec.gov.
 
    The Commission allows us to "incorporate by reference" the information we
filed with them, which means that we can disclose important information by
referring you to those documents. The information incorporated by reference is
considered to be a part of this prospectus, and information that we file later
with the Commission will automatically update and supersede this information. We
incorporate by reference the documents listed below and any future filings made
by us with the Commission under Sections 13(a), 13(c), 14 or 15(d) of the
Exchange Act until our offering is complete:
 
    - Lattice's Annual Report on Form 10-K for the fiscal year ended March 28,
      1998;
 
    - Lattice's Quarterly Reports on Form 10-Q for the fiscal quarters ended
      January 2, 1999, September 26, 1998 and June 27, 1998;
 
    - The description of Lattice's common stock which is contained in Lattice's
      registration statement on Form 8-A filed with the Commission on September
      27, 1989, including any amendment or report filed for the purpose of
      updating any such description; and
 
    - The description of the preferred stock purchase rights of Lattice
      contained in Lattice's registration statement on Form 8-A filed with the
      Commission on September 13, 1991.
 
                                       9

    You may request a copy of these filings, at no cost, by writing or
telephoning us at the following address:
 
   
    Chief Financial Officer
    Lattice Semiconductor Corporation
    5555 N.E. Moore Court
    Hillsboro, Oregon 97124-6421
    (503) 268-8000
    
 
    You should rely only on the information contained in this document or to
which we have referred you. We have not authorized anyone to provide you with
information that is different. This document may only be used where it is legal
to sell these securities. The information in this document may only be accurate
as of the date on the front of this document.
 
                                       10

                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 14.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.
 

                                                           
Securities and Exchange Commission registration fee.........  $   666.77
Fees and expenses of counsel................................    8,000.00
Fees and expenses of accountants............................    2,000.00
Blue sky fees and expenses..................................    1,500.00
Miscellaneous...............................................      333.23
                                                              ----------
    Total...................................................  $12,500.00
                                                              ----------
                                                              ----------

 
    Except for the Securities and Exchange Commission registration fee, all of
the foregoing expenses have been estimated. All of the above expenses will be
paid by Lattice.
 
ITEM 15.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
    Lattice's Certificate of Incorporation (the "Certificate") limits, to the
maximum extent permitted by Delaware law, the personal liability of directors
for monetary damages for their conduct as a director. Lattice's Bylaws provide
that Lattice shall indemnify its officers and directors and may indemnify its
employees and other agents to the fullest extent permitted by law.
 
    Section 145 of the Delaware General Corporation Law ("Delaware Law")
provides that a corporation may indemnify a director, officer, employee or agent
made a party to an action by reason of the fact that he was a director, officer,
employee or agent of the corporation or was serving at the request of the
corporation against expenses actually and reasonably incurred by him in
connection with such action if he acted in good faith and in a manner he
reasonably believed to be in, or not opposed to, the best interests of the
corporation and with respect to any criminal action, had no reasonable cause to
believe his conduct was unlawful.
 
    Delaware Law does not permit a corporation to eliminate a director's duty of
care, and the provisions of the Certificate have no effect on the availability
of equitable remedies such as injunction or rescission, based upon a director's
breach of the duty of care. Insofar as indemnification for liabilities arising
under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), may
be permitted to foregoing provisions and agreements, the Registrant has been
informed that in the opinion of the staff of the Commission such indemnification
is against public policy as expressed in the Exchange Act and is therefore
unenforceable.
 
ITEM 16.  EXHIBITS.
 


  EXHIBIT
  NUMBER                                              DESCRIPTION
- -----------  ----------------------------------------------------------------------------------------------
          
       4.1   Form of Warrant to Purchase Shares of Common Stock dated May 5, 1998.*
 
       5.1   Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation, Counsel to the
               Registrant.*
 
      23.1   Consent of PricewaterhouseCoopers LLP, Independent Accountants.
 
      23.2   Consent of Wilson Sonsini Goodrich & Rosati, Professional Corporation, Counsel to the
               Registrant (included in Exhibit 5.1).*
 
      24.1   Power of Attorney (see page II-3 of the initial filing of this Form S-3).*

 
- ------------------------
 
*   Previously filed.
 
                                      II-1

ITEM 17.  UNDERTAKINGS.
 
    (a) The Registrant hereby undertakes:
 
        (1) To file, during any period in which offers or sales are being made,
    a post-effective amendment to this Registration Statement to include any
    material information with respect to the plan of distribution not previously
    disclosed in the Registration Statement or any material change to such
    information in the Registration Statement.
 
        (2) That, for the purpose of determining any liability under the
    Securities Act, each such post-effective amendment shall be deemed to be a
    new registration statement relating to the securities offered therein, and
    the offering of such securities at that time shall be deemed to be the
    initial bona fide offering thereof.
 
        (3) To remove from registration by means of a post-effective amendment
    any of the securities being registered which remain unsold at the
    termination of the offering.
 
    (b) The Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act, each filing of the Registrant's Annual
Report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and,
where applicable, each filing of an employee benefit plan's annual report
pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference
in the Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.
 
    (c) Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.
 
                                      II-2

                                   SIGNATURES
 
   
    Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-3 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Hillsboro, State of Oregon, on March 19, 1999.
    
 

                               
                                LATTICE SEMICONDUCTOR CORPORATION
 
                                By:              /s/ CYRUS Y. TSUI
                                     -----------------------------------------
                                                   Cyrus Y. Tsui
                                         PRESIDENT, CHIEF EXECUTIVE OFFICER
                                             AND CHAIRMAN OF THE BOARD

 
    Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated:
 
   


        SIGNATURE                       TITLE                      DATE
- -------------------------  -------------------------------  -------------------
 
                                                      
                           President, Chief Executive
    /s/ CYRUS Y. TSUI        Officer (Principal Executive
- -------------------------    Officer) and Chairman of the     March 19, 1999
      Cyrus Y. Tsui          Board of Directors
 
                           Senior Vice President, Chief
  /s/ STEPHEN A. SKAGGS      Financial Officer (Principal
- -------------------------    Financial Officer) and           March 19, 1999
    Stephen A. Skaggs        Secretary
 
            *
- -------------------------  Director                           March 19, 1999
    Mark O. Hatfield
 
            *
- -------------------------  Director                           March 19, 1999
     Daniel S. Hauer
 
            *
- -------------------------  Director                           March 19, 1999
     Harry A. Merlo
 
            *
- -------------------------  Director                           March 19, 1999
    Larry W. Sonsini
 
            *
- -------------------------  Director                           March 19, 1999
    Douglas C. Strain

    
 

                                                    
*By:  /s/ STEPHEN A. SKAGGS
      -------------------------
      Stephen A. Skaggs,
      ATTORNEY-IN-FACT

 
                                      II-3

                       LATTICE SEMICONDUCTOR CORPORATION
                       REGISTRATION STATEMENT ON FORM S-3
                               INDEX TO EXHIBITS
 


  EXHIBIT
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
          
       4.1   Form of Warrant to Purchase Shares of Common Stock dated May 5, 1998.*
 
       5.1   Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation, Counsel to the Registrant.*
 
      23.1   Consent of PricewaterhouseCoopers LLP, Independent Accountants.
 
      23.2   Consent of Wilson Sonsini Goodrich & Rosati, Professional Corporation, Counsel to the Registrant
               (included in Exhibit 5.1).*
 
      24.1   Power of Attorney (see page II-3 of the initial filing of this Form S-3).*

 
- ------------------------
 
*   Previously filed.