FUNCTIONAL BLOCK DIAGRAMS

REV. A

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a

+3 V, Voltage Monitoring

P Supervisory Circuits

FEATURES

Precision Supply-Voltage Monitor

+2.63 V (ADM706P/R, ADM708R)

+2.93 V (ADM706S, ADM708S)

+3.08 V (ADM706T, ADM708T)

100

A Quiescent Current

200 ms Reset Pulsewidth

Debounced Manual Reset Input (

MR)

Independent Watchdog Timer—1.6 sec Timeout

(ADM706x)

Reset Output

Active High (ADM706P)

Active Low (ADM706R/S/T)

Both Active High and Active Low (ADM708R/S/T)

Voltage Monitor for Power-Fail or Low Battery Warning

Guaranteed

RESET Valid with V

Superior Upgrade for MAX706P/R/S/T, MAX708R/S/T

APPLICATIONS

Microprocessor Systems

Computers

Controllers

Intelligent Instruments

Critical

P Monitoring

Automotive Systems

Battery Operated Systems

Portable Instruments

GENERAL DESCRIPTION

The ADM706P/R/S/T and the ADM708R/S/T microprocessor

supervisory circuits are suitable for monitoring either 3 V or 3.3 V

power supplies.

The ADM706P/R/S/T provide the following functions:

1. Power-supply monitoring circuitry which generates a Reset

output during power-up, power-down and brownout condi-

as 1 V.

2. Independent watchdog monitoring circuitry which is acti-

vated if the watchdog input has not been toggled within

1.6 seconds.

3. A 1.25 V threshold detector for power fail warning, low bat-

tery detection, or to monitor an additional power supply.

4. An active low debounced manual reset input (

MR).

The ADM706R, ADM706S, ADM706T are identical except for

the reset threshold monitor levels which are 2.63 V, 2.93 V, and

3.08 V respectively. The ADM706P is identical to the ADM706R

in that the reset threshold is 2.63 V. It differs only in that it has

an active high reset output.

ADM706P/R/S/T, ADM708R/S/T

The ADM708R/S/T provide the same functionality as the

ADM706R/S/T and only differ in that:

1.

A watchdog timer function is not available.

2.

An active high reset output (RESET) in addition to the

active low (

RESET) output is available.

All parts are available in 8-lead DIP and narrow SOIC packages.

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

Tel: 781/329-4700

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

Fax: 781/326-8703

© Analog Devices, Inc., 1999

WATCHDOG

TRANSITION

DETECTOR

WATCHDOG

TIMER

1.25V

WATCHDOG

INPUT (WDI)

POWER FAIL

INPUT (PFI)

POWER FAIL

OUTPUT (

PFO)

WATCHDOG

OUTPUT(

WDO)

RESET,

(P = RESET)

ADM706

RESET &

WATCHDOG

TIMEBASE

RESET

GENERATOR

MR

70 A

1.25V

POWER FAIL

INPUT (PFI)

POWER FAIL

OUTPUT (

PFO)

RESET

ADM708

RESET

GENERATOR

MR

70 A

RESET