Also included is a watchdog timer to stop and restart a

microprocessor that is “hung-up”. Three watchdog time-

out periods are selectable: 150ms, 610ms and 1,200ms. If the

ST input is not strobed LOW before the time-out period

expires, a reset is issued.

Devices are available in 8-pin DIP, 8-pin SO and compact

8-pin MicroSO packages.

©

1999 IMP, Inc.

408-432-9100/www.impweb.com

1

Key Features

x

Pin compatible with the Dallas Semiconductor

DS1832

— Over 40% lower supply current

x

3.3V supply monitor

x

Push-pull output

x

Selectable watchdog period

x

Debounce manual push-button reset input

x

Precision temperature-compensated voltage

reference and comparator

x

Power-up, power-down and brownout detection

x

250ms minimum reset time

x

Active LOW and HIGH reset signal

x

Selectable trip point tolerance: 10% or 20%

x

Low-cost 8-pin DIP/SO and 8-pin MicroSO

packages

x

Wide operating temperature – 40

°C to +85°C

Block Diagram

RESET

PBRST

1

1832_02.eps

40k

9

TOL

IMP1832

3

–

+

10%/20% Tolerance

Selection

Reference

8

6

TD

Push Button

Debounce

2

Watchdog

Timebase Selection

GND

4

Reset &

Watchdog Timer

ST

7

Watchdog

Transition Detector

RESET

5

IMP1

832

3.3V

Monit

cuit

– Select

ance and

W

iod

– Push-Butt

eset

– Push-Pull R

eset Outputs

The IMP1832 microprocessor supervisor can halt and restart a “hung-

up” or “stalled” microprocessor, restart a microprocessor after a power

failure, and debounce a manual push-button microprocessor reset

switch. The IMP1832 features over 40% lower supply current than the

pin compatible Dallas Semiconductor DS1832.

Precision temperature compensated reference and comparator circuits

power supply falls outside selectable tolerance limits, both RESET and

reset signals remain active for an additional 250ms minimum, allowing

the power supply and system microprocessor to stabilize. The trip point

tolerance signal, TOL, selects the trip level tolerance to be either 10- or

20-percent.

RESET and RESET outputs are push-pull.

A debounced manual reset input, PBRST, activates the reset outputs for

a minimum period of 250ms.