The MAX791 microprocessor (µP) supervisory circuit reduces the complexity and number of components needed to monitor power-supply and battery-control functions in µP systems. It is characterized by low power consumption and fast response time, making it suitable for both portable equipment and high-performance equipment. The MAX791 provides various functions, including µP reset, manual reset input, power-fail and low-battery detection, backup-battery switchover, software monitoring of backup-battery voltage, watchdog-fault output, and write protection of CMOS RAM or EEPROM.