Unit for maintaining information regarding the state of a device during battery power

摘要

A unit for maintaining the value of information regarding the state of a device during battery power includes one local latch per bit of state to be maintained. The latch is powered by a switched power supply which switches between main and battery power supplies. The latch latches the value of the bit of state when the value of the bit of state is valid and the power of the device is significant and maintains the value otherwise, typically during battery operation.