DESCRIPTION
   The X4643/5 combines four popular functions, Power-on 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