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ManualsBrandsANALOG DEVICES ManualsPMICsPMIC - system monitor Reset/power-on reset PDIP 8

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Microprocessor

Supervisory Circuits

ADM698/ADM699

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

Tel: 617/329-4700 Fax: 617/326-8703

FUNCTIONAL BLOCK DIAGRAM

RESET

GENERATOR

4.65V

WATCHDOG

INPUT

WDI

ADM698/

ADM699

RESET

WATCHDOG

OUTPUT WDO

RESET

WDI (ADM699 ONLY)

RESET (SOIC ONLY)

WDO (ADM699 SOIC ONLY)

WATCHDOG

TRANSITION DETECTOR

(1 sec)

TYPICAL APPLICATION CIRCUIT

ADM699 ONLY

+5V

WDI

GND

ADM698/

ADM699

RESET

µP POWER

µP SYSTEM

I/O LINE

µP RESET

FEATURES

Superior Up

grade for MAX698/MAX699

Guaranteed

RESET Assertion with V

= 1 V

Low 0.6 mA Supply Current

Precision 4.65 V Voltage Monitor

Power OK/Reset Time Delay

Watchdog Timer

Minimum Component Count

Performance Specified over Temperature

APPLICATIONS

Microprocessor Systems

Computers

Controllers

Intelligent Instruments

Automotive Systems

Critical mP Power Monitoring

GENERAL DESCRIPTION

The ADM698/ADM699 supervisory circuits provide power

supply monitoring and watchdog timing for microprocessor

systems.

The ADM698 monitors the 5 V V

power supply and gener-

ates a

RESET pulse during power up, power down and during

low voltage “Brown Out” conditions. The

RESET output is

guaranteed to be functional (logic low) with V

as low as 1 V.

The ADM699 features an identical monitoring circuit as in the

ADM698 plus an additional watchdog timer input to monitor

microprocessor activity. The

RESET output is forced low if the

watchdog input is not toggled within the 1 second watchdog

timeout period.

Both parts are available in 8-pin plastic DIP and 16-lead SOIC

packages. The 16-lead SOIC contains additional outputs

RESET (without inversion) and Watchdog Output WDO

(ADM699 only).

Summary of content (4 pages)

PAGE 1
a Microprocessor Supervisory Circuits ADM698/ADM699 FEATURES Superior Upgrade for MAX698/MAX699 Guaranteed RESET Assertion with VCC = 1 V Low 0.6 mA Supply Current Precision 4.
PAGE 2
ADM698/ADM699–SPECIFICATIONS (V CC = +5 V 6 10%, TA = TMIN to TMAX unless otherwise noted) Parameter Min VCC Operating Voltage Range Supply Current 3.0 Power-Down Reset Assertion Power-Up Reset Deassertion Reset Threshold Hysteresis Reset Active Time 4.5 4.65 140 40 200 280 Watchdog Timeout Period (ADM699) Minimum WDI Input Pulse Width 1.0 50 1.6 4 RESET Output Voltage RESET Output Voltage (VCC = 1 V) Typ Max Units 0.6 5.5 1.95 V mA 4.73 4.73 V V mV ms TA = +25°C, VCC = +5 V 2.
PAGE 3
ADM698/ADM699 PIN CONFIGURATION (DIP) PIN FUNCTION DESCRIPTION Mnemonic VCC GND RESET WDI RESET WDO Function +5 V Power Supply Input. 0 V. Ground reference for all signals. Logic Output. RESET goes low whenever VCC falls below the reset voltage threshold (4.65 V typ). RESET remains low for a minimum of 140 ms after VCC returns to 5 V. RESET also goes low for a minimum of 140 ms if the watchdog timer is enabled but not serviced within its timeout period. Watchdog Input. WDI is a three level input.
PAGE 4
ADM698/ADM699 CIRCUIT INFORMATION Power Fail RESET The watchdog timer input (WDI) monitors an I/O line from the µP system. The µP must toggle this input once every 1.6 seconds to verify correct software execution. Failure to toggle the line indicates that the µP system is not correctly executing its program and may be tied up in an endless loop. If this happens, a reset pulse is generated to initialize the processor.