The TL7702A is a supply-voltage supervisor designed specifically for use as a reset controller in microcomputer and microprocessor systems. The supply-voltage supervisor monitors the supply for under voltage 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 under voltage condition occurs during normal operation, 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). During power down and when SENSE is below VIT?, the outputs remain active until VCC falls below 2 V. After this, the outputs are undefined. An external capacitor (typically 0.1 µF) must be connected to REF to reduce the influence of fast transients in the supply voltage.
