The TL77xxA family of integrated-circuit supply-voltage supervisors is specifically designed for use as reset controllers in microcomputer and microprocessor systems. The supply-voltage supervisor monitors the supply for undervoltage conditions at the SENSE input. During power up, the RESET output becomes active (low) when VCC attains a value approaching 3.6 V. At this point (assuming that SENSE is above VIT+), the delay timer function activates a time delay, after which outputs RESET and RESET go inactive (high and low, respectively). When an undervoltage condition occurs during normal operation, outputs RESET and RESET go active. To ensure that a complete reset occurs, the reset outputs remain active for a time delay after the voltage at the SENSE input exceeds the positive-going threshold value. The time delay is determined by the value of the external capacitor CT: td = 1.3 × 104 × CT, where CT is in farads (F) and td is in seconds (s).
