BATTERY AUXILIARY METAL OXIDE SEMICONDUCTOR 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 standby battery power. When Vcc is returned to the system, a gate applies a trickle charge to the battery.