The Watchdog Timer provides an independent protection mechanism for microcontrollers. When the microcontroller fails to restart a timer within a selectable time out interval, the device activates the RESET signal. The user selects the interval from three preset values. Once selected, the interval does not change, even after cycling the power. The device's low VCC detection circuitry protects the user's system from low voltage conditions, resetting the system when VCC falls below the minimum VCC trip point. RESET is asserted until VCC returns to the proper operating level and stabilizes. Five industry standard VTRIP thresholds are available, however, Intersil's unique circuits allow the threshold to be reprogrammed to meet custom requirements or to finetune the threshold for applications requiring higher precision.