Exhibit 5.1


September 13, 2002


Microchip Technology Incorporated
2355 West Chandler Boulevard
Chandler, AZ  85224

     Re: Registration Statement on Form S-8 For Issuance of Common Stock Under
         the Microchip Technology Incorporated 1997 Nonstatutory Stock Option
         Plan and the 2001 Employee Stock Purchase Plan ("ESPP")

Gentlemen:

I refer you to your registration on Form S-8 (the "Registration Statement")
under the Securities Act of 1933, as amended, of 5,900,000 shares of Common
Stock under the 1997 Nonstatutory Stock Option Plan and of 500,000 shares of
Common Stock under the ESPP. I advise you that, in my opinion, when such shares
have been issued and sold pursuant to the applicable provisions of the plans,
and in accordance with the Registration Statement, such shares will be validly
issued, fully-paid and non-assessable shares of the Company's Common Stock, par
value $.001 per share.

I hereby consent to the filing of this opinion as an exhibit to the Registration
Statement.

Sincerely yours,

/s/ Mary K. Simmons

Mary K. Simmons
General Counsel
Microchip Technology Incorporated