1

®

FN8113.1

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

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X4003, X4005

CPU Supervisor

FEATURES

• Selectable watchdog timer

—Select 200ms, 600ms, 1.4s, off

—Five standard reset threshold voltages

nominal 4.62V, 4.38V, 2.92V, 2.68V, 1.75V

special programming sequence

• Low power CMOS

—12µA typical standby current, watchdog on

—800nA typical standby current watchdog off

—3mA active current

• 1.8V to 5.5V power supply operation

• Available packages

—8 Ld SOIC

—8 Ld MSOP

• Pb-free plus anneal available (RoHS compliant)

DESCRIPTION

These devices combine three popular functions,

Power-on Reset Control, Watchdog Timer, and Supply

Voltage Supervision. 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

protection mechanism for microcontrollers. When the

microcontroller fails to restart a timer within a select-

able 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 the

proper operating level and stabilizes. Five industry stan-

unique circuits allow the threshold to be reprogrammed

to meet custom requirements, or to fine-tune the thresh-

old for applications requiring higher precision.

BLOCK DIAGRAM

Data

Register

Command

Decode &

Control

Logic

SDA

SCL

Reset &

Watchdog

Timebase

Power-on and

Generation

+

-

RESET (X4003)

Reset

Low Voltage

Control

Register

Watchdog Transition

Detector

WP

Reset logic

RESET (X4005)

Watchdog

Timer Reset

Data Sheet

May 11, 2006