5V Supply Voltage Supervisor, Watchdog Timer, Manual Reset, with Active High & Low Resets

The CAT1232LP voltage supervisor can halt and restart a "hung-up" or "stalled" microprocessor, restart a microprocessor after a power failure, and debounce a manual/push-button microprocessor reset switch. The device is a drop in replacement for the Maxim/Dallas Semiconductor DS1232LP supervisor.

Precision reference and comparator circuits monitor the 5V system power supply voltage, V_CC. During power-up or when the power supply falls outside selectable tolerance limits, both the RESET and RESET become active. After the power supply voltage rises above the RESET threshold voltage, the reset signals remain active for a minimum of 250ms, allowing the power supply and system processor to stabilize. The trip-point tolerance input, TOL, selects the trip level tolerance to be either 5% or 10% for the CAT1232LP 5V supply.

The device has a push-pull, active HIGH reset output. The CAT1232LP also has an open drain, active LOW reset output.

A debounced manual reset input activates the reset outputs and holds them active for a minimum period of 250ms after being released.

Also included is a watchdog timer to reset a microprocessor that has stopped due to a software or hardware failure. Three watchdog time-out periods are selectable: 150ms, 600ms and 1.2sec. If the ST input is not strobed low before the watchdog time out period expires, the reset signals become active for a minimum of 250ms.