View ds1231 d datasheet:

DS1231/S DS1231/S Power Monitor Chip FEATURES PIN ASSIGNMENT • Warns processor of an impending power failure 1 8 IN VCC • Provides time for an orderly shutdown 2 NMI 7 MODE • Prevents processor from destroying nonvolatile 3 RST 6 TOL memory during power transients 4 5 RST GND • Automatically restarts processor after power is DS1231 8–Pin DIP restored (300 MIL) See Mech. Drawings • Suitable for linear or switching power supplies Section • Adjusts to hold time of the power supply NC NC 1 16 15 VCC IN 2 • Supplies necessary signals for processor interface NC NC 3 14 MODE 13 NMI 4 • Accurate 5% or 10% VCC monitoring NC 5 NC 12 • Replaces power-up reset circuitry TOL 6 11 RST 7 10 NC NC • No external capacitors required GND 9 8 RST • Optional 16-pi