Method of and apparatus for achieving “watch dog” functions in microcontrollers and microcomputers and the like, required to shut down for extended periods of time for energy-conservation purposes

摘要

A watchdog timer circuit modified to operate during periods of microcomputer shut-down or sleeping, as for energy conservation purposes, controlled by an independent external rectangular-wave signal for inhibiting watchdog timer reset signal generation for the microcomputer during such shut-down periods and until a wake-up signal is generated at the end of such microcomputer sleeping, whereupon the watchdog circuit will generate a reset signal in the absence of proper microcomputer operation.