As may be implemented in accordance with one or more embodiments, an event manager provides control of a battery-powered internal power supply. The power supply has a control port that receives a control signal for activating and deactivating the internal power supply, and one or more output ports for providing a power signal. The event manager includes a plurality of system-event circuits that detect activity signals corresponding to a respective one of a plurality of system events. An event validation circuit, which is powered by the power signal, provides a validation signal that is based upon an activity signal detected by the event manager circuit and that indicates that the internal power supply should provide the power signal in a non-sleep power-operation mode.