Notwithstanding the period of irrevocability specified, the proxy becomes revocable when the agreement to purchase is terminated; the debt of the corporation or the member is paid; or the period of employment provided for in the contract of employment has terminated. In addition to the foregoing paragraphs (1) through (3), a proxy of a member 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 § 7613