Exhibit 5.1

                      Paul, Hastings, Janofsky & Walker LLP
         515 South Flower Street, 25th Floor, Los Angeles, CA 90071-2228
 telephone 213-683-6000 / facsimile 213-627-0705 / internet www.paulhastings.com





September 3, 2004                                                    11328.74011

Semtech Corporation
200 Flynn Road
Camarillo, California 93012

Ladies and Gentlemen:

We are furnishing this opinion of counsel to Semtech Corporation, a Delaware
corporation (the "Company"), for filing as Exhibit 5.1 to the Registration
Statement on Form S-8 (the "Registration Statement") to be filed by the Company
with the Securities and Exchange Commission under the Securities Act of 1933, as
amended, relating to the issuance and sale by the Company of up to 4,902,200
shares of its Common Stock (the "Shares") upon the exercise of stock options or
awards granted pursuant to the Company's Long-Term Stock Incentive Plan (the
"Plan").

We have examined the Certificate of Incorporation and Bylaws, each as amended to
date, of the Company, and the originals, or copies certified or otherwise
identified, of records of corporate action of the Company as furnished to us by
the Company, certificates of public officials and of representatives of the
Company, and such other instruments and documents as we deemed necessary, as a
basis for the opinions hereinafter expressed. In such examination we have
assumed the genuineness of all signatures, the authenticity of all corporate
records and other documents submitted to us and the conformity to original
documents submitted to us as certified or photostatic copies.

Based upon our examination as aforesaid, and in reliance upon our examination of
such questions of law as we deem relevant under the circumstances, we are of the
opinion that the Shares, when purchased and issued as described in the
Registration Statement and in accordance with the Plan (including the receipt of
the full purchase price therefor), will be validly issued, fully paid and
nonassessable.

We express no opinion with respect to the applicability or effect of the laws of
any jurisdiction other than the Delaware General Corporation Law, as in effect
as of the date hereof.

We hereby consent to the filing of this opinion of counsel as Exhibit 5.1 to the
Registration Statement.

Very truly yours,

/s/ Paul, Hastings, Janofsky & Walker LLP