The MAX690 family of supervisory circuits reduces the complexity and number of components required for power supply monitoring and battery control functions in microprocessor systems. These include µP reset and backup-battery switchover, watchdog timer, CMOS RAM write protection, and power-failure warning. The MAX690 family significantly improves system reliability and accu- racy compared to that obtainable with separate ICs or discrete components.

The MAX690, MAX692, and MAX694 are supplied in 8-pin packages and provide four functions:

• A reset output during power-up, power-down, and brownout conditions.
• Battery backup switching for CMOS RAM, CMOS microprocessor or other low power logic.
• A Reset pulse if the optional watchdog timer has not been toggled within a specified time.
• A 1.3V threshold detector for power fail warning, low battery detection, or to monitor a power supply other than +5V.

The MAX691, MAX693, and MAX695 are supplied in 16-pin packages and perform all MAX690, MAX692, MAX694 functions, plus:

• Write protection of CMOS RAM or EEPROM.
• Adjustable reset and watchdog timeout periods.
• Separate outputs for indicating a watchdog timeout, backup-battery switchover, and low VCC.