DESCRIPTION
   The X4643/5 combines four popular functions, Poweron Reset Control, Watchdog Timer, Supply Voltage Supervision, and Serial EEPROM Memory in one package. This combination lowers system cost, reduces board space requirements, and increases reliability.

FEATURES
• Selectable watchdog timer
• Low VCC detection and reset assertion
   —Four standard reset threshold voltages
   —Adjust low VCC reset threshold voltage using
      special programming sequence
   —Reset signal valid to VCC = 1V
• Low power CMOS
   —<20µA max standby current, watchdog on
   —<1µA standby current, watchdog off
   —3mA active current
• 64Kbits of EEPROM
   —64-byte page write mode
   —Self-timed write cycle
   —5ms write cycle time (typical)
• Built-in inadvertent write protection
   —Power-up/power-down protection circuitry
• 400kHz 2-wire interface
• 2.7V to 5.5V power supply operation
• Available packages
   —8-lead SOIC
   —8-lead TSSOP