Exhibit 99.1 CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 I, Steve Sanghi, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Quarterly Report of Microchip Technology Incorporated on Form 10-Q for the quarterly period ended December 31, 2002 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of Microchip Technology Incorporated. By: /s/ Steve Sanghi ------------------------------------ Name: Steve Sanghi Title: President and Chief Executive Officer Date: February 7, 2003 I, Gordon W. Parnell, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Quarterly Report of Microchip Technology Incorporated on Form 10-Q for the quarterly period ended December 31, 2002 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of Microchip Technology Incorporated. By: /s/ Gordon W. Parnell ------------------------------------ Name: Gordon W. Parnell Title: Vice President and Chief Financial Officer Date: February 7, 2003