(1) A director may resign at any time by delivering written notice to the board of directors or its chair or to the corporation.
(2) A resignation is effective when the notice is delivered unless the notice specifies a later effective date or an effective date determined upon the subsequent happening of an event. If a resignation is made effective at a later date or upon the subsequent happening of an event, 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 may provide that the resignation is irrevocable.