CPU Supervisor and System Management Devices for Battery Applications: Using the X40420, X40421 as a Battery Backup Switch CPU Supervisor and System Management Devices for Battery Applications: Using the X40420, X40421 as a Battery Backup Switch Application Note July 15, 2005 AN164.0 Author: Carlos Martinez Introduction The X40420, X40421 devices have a Power On Reset (POR) circuit, low voltage monitors for two supplies, an automatic switch between a main voltage source and a backup supply, a watchdog timer, 4kbits of EEPROM and a fault detection register. Some of these……