View ds1233a datasheet:

DS1233A 3.3V EconoReset www.maxim-ic.com FEATURES PIN ASSIGNMENT Automatically restarts microprocessor after power failure DALLAS DS1233A Monitors pushbutton for external override Econo Reset Internal circuitry debounces pushbutton switch Maintains reset for 350ms after VCC returns to an in-tolerance condition or pushbutton released 1 Accurate 10% or 15% microprocessor 3.3V 1 2 3 power supply monitoring Reduces need for discrete components 1 2 3 Precision temperature-compensated voltage 2 4 3 reference and voltage sensor BOTTOM VIEW TOP VIEW Low-cost TO-92 package or surface mount TO-92 PACKAGE SOT-223 PACKAGE See Mech. See Mech. SOT-223 package Drawings Section Drawings Section Internal 5k pull-up resistor on Website on Website Op