Affiliation Agreement

EXHIBIT 10.5 AFFILIATION AGREEMENT THIS AGREEMENT (the " Agreement" ) is made as of October 3, 2007 between Allegro MicroSystems, Inc., a Delaware corporation with its principal offices at 115 Northeast Cutoff, Worcester, Massachusetts 01615 (" Allegro" ); and Sanken Electric Co., Ltd., a Japanese corporation with its principal offices at 3-6-3 Kitano, Niiza-shi, Saitama, Japan (" Sanken" ). WHEREAS , Allegro anticipates an initial public offering (" IPO" ) of its common stock, after which Allegro will become a public company; and WHEREAS, the parties wish to clarify the contractual relationships between Allegro and Sanken and between Allegro and Polar Semiconductor, Inc. (" PSI" ), a wholly-owned subsidiary of Sanken located in Bloomington, Minnesota; and WHEREAS , the parties wish to anticipate their communications and exchanges of information after the IPO, and provide for appropriate treatment of information that is confidential or non-public. NOW, THEREFORE , the parties hereby agree as follows: 1. Formal Agreements . Allegro and Sanken (collectively referred to as " Parties" and singularly as " Party" ) acknowledge that Allegro is a party to those written agreements with Sanken and/or PSI that are set forth on Exhibit A to this Agreement. 2. Terminated Agreements . The Parties acknowledge that those written agreements between Sanken and Allegro that are set forth on Exhibit B have terminated or expired, and if not terminated or expired as of the date of this Agreement, such agreements are hereby terminated pursuant to this Agreement. 3. Confidentiality . Without limiting any rights or obligations under any existing or future agreement between the Parties concerning confidentiality, the Parties agree not to disclose to any third party without written authorization of the disclosing Party any Confidential Information received from the disclosing Party, and further, to use the same standard of care it employs for the protection of its own confidential information to prevent


Confidential Information originating with the disclosing Party from being disclosed to any third party outside its employ for a term of five (5) years from the date of the respective disclosure and to disclose such information to its employees only on a need-to-know basis. As used in this Agreement " Confidential Information" shall include but not be limited to all information regarding patents, products, designs, marketing plans, processes, inventions, formulae, pricing and cost information, specifications, drawings, samples or other confidential or proprietary information or data furnished by one Party to the other.For purposes of this Agreement, all Confidential Information disclosed either orally or in writing, whether identified as confidential or not, will be considered by the Parties to be " Confidential Information" unless the disclosed information (a) was in the receiving Party' s possession before receipt from the disclosing Party; (b) is or becomes a matter of public knowledge through no fault of the Receiving party; (c) is rightfully received by the receiving Party from a rightfully possessing third party without a duty of confidentiality; (d) is required to be disclosed by court order or other lawful governmental actions, but only to the extent so ordered, and provided that the Party so ordered shall notify the disclosing Party so that the disclosing Party may attempt to obtain a protective order; or (e) is independently developed by an employee of the receiving Party who has not had access to any Confidential Information of the disclosing Party. A Party may disclose Confidential Information to the Party' s employees, agents or subcontractors as reasonably necessary or appropriate, provided that before disclosure such recipients are informed of the confidential nature of the Confidential Information and the disclosing Party shall ensure compliance by its employees, agents or subcontractors with the confidentiality provisions of this Agreement.No license to the receiving Party under any patent or other property of the disclosing Party is granted or implied by disclosing Confidential Information or any other information to the receiving Party. None of such disclosed information which may be transmitted or exchanged by the respective Parties shall constitute any representation, warranty, assurance, guaranty, or inducement by either Party to the other with respect to the Confidential Information, including but not limited to non-infringement of patents or other proprietary rights of any third party. 4. Non-Public Information . The Parties agree that for so long as a Party is in possession of any material non-public information regarding the other Party or any securities issued by the other Party, as the term " material non-public information" is used in Regulation FD promulgated by the U.S. Securities and Exchange Commission, such Party (a) will maintain such material non-public information in confidence; and (b) will not purchase, sell, or otherwise engage in any similar transaction relating to, the securities of the other Party.

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5. Exchange of Business Information .The Parties maintain a strategic business relationship and engage in substantial transactions on an ongoing basis, including without limitation purchase and sale of products, joint technology development and loan transactions. Allegro is a major customer of PSI and has other substantial business relationships with PSI. The financial results of Allegro must be consolidated into Sanken' s financial state ...