January 2006

1

MIC1832

MIC1832

Micrel, Inc.

MIC1832

µP Supervisory Circuit

General Description

The MIC1832 is a multifunction circuit which monitors mi-

croprocessor activity, external reset and power supplies in

microprocessor based systems. The circuit functions include

awatchdogtime,powersupplymonitor,microprocessorreset,

and manual pushbutton reset input.

The power supply line is monitored with a comparator and

an internal voltage reference. /RST is forced low when an

out-of-tolerance condition exists and remains asserted for

(2.55V or 2.88V). The /RST pin will remain logic low with

The Watchdog input (/ST) monitors µP activity and will as-

sert /RST if no µP activity has occurred with in the watchdog

timeout period. The watchdog timeout period is selectable

with nominal period of 150, 600, 1200 milliseconds.

Typical Application

VCC

RST

µP

RESET

VCC

MIC1832

VCC

PBRST

TOL GND

ST

I/O

TD

Features

• Power OK/Resettime delay, 250ms min.

• Watchdog timer, 150ms, 600ms, or 1.2s typical

• Precision supply voltage monitor, select between 5% or

10% of supply voltage

• Avaiable in 8-pin surface mount (SO)

• Debounced External reset input

• Low supply current, <18µA typical

Applications

• Autimotive systems

• Intelligent systems

• Critical microprocessor power monitoring

• Battery powered computers

• Controllers

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

Ordering Information

Part Number

Temperature Range

Package

Standard

Pb-Free

MIC1832N

MIC1832NY

–40ºC to +85ºC

8-Pin PDIP

MIC1832M

MIC1832MY

–40ºC to +85ºC

8-Pin SOIC