Notwithstanding the period of irrevocability specified, the proxy becomes revocable when the pledge is redeemed, the option or agreement to purchase is terminated or the seller no longer owns any shares of the corporation or dies, the debt of the corporation or the shareholder is paid, the period of employment provided for in the contract of employment has terminated, the agreement under Section 706 has terminated, or the person ceases to be a beneficiary of the trust. In addition to the foregoing clauses (1) through (5), a proxy may be made irrevocable (notwithstanding subdivision (c)) if it is given to secure the performance of a duty or to protect a title, either legal or equitable, until the happening of events which, by its terms, discharge the obligations secured by it.
Ca. Corp. Code § 705