MOS BATTERY BACKUP CONTROLLER FOR MICROCOMPUTER RANDOM ACCESS MEMORY

摘要

MOS control circuitry for incorporation on a microcomputer IC chip for assuring adequate power to maintain the data in an associated static random access memory, A rechargeable battery provides standby power, and the voltage level of the battery is compared with the microcomputer Vcc supply. Whenever Vcc drops below a predetermined level, such as the standby }battery voltage level , the circuitry disconnects the Vcc from the memory input power and replaces it with s standby battery power. When Vcc is returned to the system, a gate applies a trickle charge to the battery.