(1) A director may resign at any time by delivering written notice of resignation to the board of directors or its chair or to the secretary of the corporation.
(2) A resignation is effective when the notice of resignation is delivered unless the notice of resignation specifies a later effective date or an effective date determined upon the subsequent happening of an event or events. If a resignation is made effective at a later date or upon the subsequent happening of an event or events, the board of directors may fill the pending vacancy before the effective date occurs if the board of directors provides that the successor does not take office until the effective date.
(3) A resignation that specifies a later effective date or that is conditioned upon the subsequent happening of an event or events or upon failing to receive a specified vote for election as a director may provide that the resignation is irrevocable.