The MIC1232 is a multifunction circuit which monitors microprocessor activity, external reset and power supplies in microprocessor based systems. The circuit functions include a watchdog time, power supply monitor, microprocessor reset, and manual pushbutton reset input. The power supply line is monitored with a comparator and an internal voltage reference. /RST is forced low when an out-of-tolerance condition exists and remains asserted for at least 250ms after VCC rises above the threshold voltage (4.5V or 4.75V). The /RST pin will remain logic low with VCC as low as 1.4V. The Watchdog input (/ST) monitors µP activity and will assert /RST if no µP activity has occurred with in the watchdog timeout period. The watchdog timeout period is selectable with nominal period of 150, 600, 1200 milliseconds.