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a

ADM809/ADM810

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1997

Microprocessor

Supervisory Circuit in 3-Pin SOT-23

FUNCTIONAL BLOCK DIAGRAM

RESET

GENERATOR

240ms

ADM809/ADM810

RESET

(RESET)

GND

FEATURES

Superior Upgrade for MAX809/MAX810

Specified Over Temperature

Low Power Consumption (17

A)

Precision Voltage Monitor: +3 V, +3.3 V, +5 V Options

140 ms min Power-On Reset

Logic Low

RESET Output (ADM809)

Logic High RESET Output (ADM810)

APPLICATIONS

Microprocessor Systems

Computers

Controllers

Intelligent Instruments

Automotive Systems

GENERAL DESCRIPTION

The ADM809/ADM810 supervisory circuits monitor the

power supply voltage in microprocessor systems. They pro-

vide a reset output during power-up, power-down and

brownout conditions. On power-up, an internal timer holds

reset asserted for 240 ms. This holds the microprocessor in a

reset state until conditions have stabilized. The

RESET

ADM809 provides an active low reset signal (

RESET) while

the ADM810 provides an active high signal (RESET) output.

Six reset threshold voltage options are available suitable for

monitoring a variety of supply voltages. Refer to Table I.

The reset comparator features built-in glitch immunity,

The ADM809/ADM810 consumes only 17

µA, making it

suitable for low power portable equipment. It is packaged in

a 3-pin SOT-23 package.

RESET

RESET

INPUT

GND

GND

µP

SYSTEM

ADM809

Figure 1. Typical Operating Circuit