1

®

FN8123.0

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 1-888-352-6832

Copyright Intersil Americas Inc. 2005. All Rights Reserved

All other trademarks mentioned are the property of their respective owners.

X4643, X4645

64K, 8K x 8 Bit

CPU Supervisor with 64K EEPROM

FEATURES

• Selectable watchdog timer

—Four standard reset threshold voltages

special programming sequence

• 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

DESCRIPTION

The X4643/5 combines four popular functions, Power-

on Reset Control, Watchdog Timer, Supply Voltage

Supervision, and Serial EEPROM Memory in one pack-

age. This combination lowers system cost, reduces

board space requirements, and increases reliability.

Applying power to the device activates the power-on

reset circuit which holds RESET/RESET active for a

period of time. This allows the power supply and oscilla-

tor to stabilize before the processor can execute code.

The Watchdog Timer provides an independent protec-

tion mechanism for microcontrollers. When the micro-

controller fails to restart a timer within a selectable time

out interval, the device activates the RESET/RESET

signal. The user selects the interval from three preset

values. Once selected, the interval does not change,

even after cycling the power.

user’s system from low voltage conditions, resetting

returns to proper operating level and stabilizes. Four

however, Intersil’s unique circuits allow the threshold

to be reprogrammed to meet custom requirements or

to fine-tune the threshold for applications requiring

higher precision.

BLOCK DIAGRAM

Watchdog

Timer Reset

Data

Register

Command

Decode &

Control

Logic

SDA

SCL

Reset &

Watchdog

Timebase

Power-on and

Generation

+

-

RESET (X4643/5)

Reset

Low Voltage

Status

Register

Protect Logic

EEPROM Array

Watchdog Transition

Detector

WP

Reset Logic

RESET (X4645)

S0

S1

Data Sheet

March 29, 2005