EXHIBIT 5.1

                         OPINION OF COOLEY GODWARD LLP

October 23, 2000

IXYS Corporation
3540 Bassett Street
Santa Clara, CA 95054

Ladies and Gentlemen:

      You have requested our opinion with respect to certain matters in
connection with the filing by IXYS Corporation (the "Company") of a
Registration Statement on Form S-3 (the "Registration Statement") with the
Securities and Exchange Commission covering an underwritten public offering of
up to 4,600,000 shares of common stock, par value $0.01 per share, including
2,000,000 shares to be sold by the Company (the "Company Shares"), and
2,000,000 shares to be sold by selling stockholders, plus 600,000 shares to be
sold by one of the selling stockholders upon exercise of the over-allotment
option (the "Selling Stockholder Shares"). The Company Shares and the Selling
Stockholder Shares are collectively referred to herein as "Common Stock."

      In connection with this opinion, we have examined and relied upon the
Registration Statement and related Prospectus, the Company's Certificate of
Incorporation and Bylaws, as amended, the resolutions adopted by the Board of
Directors of the Company on September 14, 2000, and the originals or copies
certified to our satisfaction of such other documents, records, certificates,
memoranda and other instruments as in our judgment are necessary or appropriate
to enable us to render the opinion expressed below. We have assumed the
genuineness and authenticity of all documents submitted to us as originals, the
conformity to originals of all documents submitted to us as copies thereof, and
the due execution and delivery of all documents where due execution and
delivery are a prerequisite to the effectiveness thereof. We have also assumed
that the shares of Common Stock will be sold by the Underwriters at a price
established by the Pricing Committee of the Board of Directors of the Company.

      On the basis of the foregoing, and in reliance thereon, we are of the
opinion that the Company Shares, when sold and issued in accordance with the
Registration Statement and related Prospectus, will be validly issued, fully
paid and nonassessable.

      We consent to the reference to our firm under the caption "Legal Matters"
in the Prospectus included on the Registration Statement and to the filing of
this opinion as an exhibit to the Registration Statement.

                                          Sincerely,

                                          COOLEY GODWARD LLP

                                                    /s/ James R. Jones
                                          By: _________________________________
                                                       James R. Jones