ADM8690ANZ Datasheet ADM8695ARWZ, ADM8691ARNZ, ADM8690ARNZ | P1-P3

Microprocessor

Supervisory Circuits

Data Sheet

ADM8690/ADM8691/ADM8695

Rev. C

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FEATURES

Upgrade for the ADM690, ADM691, ADM695 and

for the MAX690, MAX691, MAX695

Specified over temperature

Low power consumption: 0.7 mW

Precision voltage monitor

Reset assertion down to 1 V V

Low switch on resistance: 0.7 Ω normal, 7 Ω in backup

High current drive: 100 mA

Watchdog timer: 100 ms, 1.6 sec, or adjustable

Standby current: 400 nA

Automatic battery backup power switching

Extremely fast gating of chip enable signals (3 ns)

Voltage monitor for power fail

Available in TSSOP package

APPLICATIONS

Microprocessor systems

Computers

Controllers

Intelligent instruments

Automotive systems

PRODUCT HIGHLIGHTS

The ADM8690 is available in 8-lead PDIP and SOIC packages

and provides the following functions:

1. Power-on reset output during power-up, power-down,

and brownout conditions. The

RESET

output remains

operational with V

as low as 1 V.

2. Battery backup switching for CMOS RAM, CMOS micro-

processor, or other low power logic.

3. Reset pulse if the optional watchdog timer is not toggled

within a specified time.

4. 1.3 V threshold detector for power-fail warning, low battery

detection, or to monitor a power supply other than 5 V.

The ADM8691 and ADM8695 are available in 16-lead PDIP

and small outline packages (including TSSOP) and provide

three additional functions:

1. Write protection of CMOS RAM or EEPROM.

2. Adjustable reset and watchdog timeout periods.

3. Separate watchdog timeout, backup battery switchover, and

low V

status outputs.

FUNCTIONAL BLOCK DIAGRAMS

RESET

1.3V

RESET

GENERATOR

WATCHDOG

TRANSITION DETECTOR

(1.6sec)

4.65V

ADM8690

WATCHDOG

INPUT (WDI)

POWER-FAIL

INPUT (PFI)

BATT

OUT

OUTPUT (PFO)

VOLTAGE DETECTOR = 4.65V

RESET PULSE WIDTH = 50ms

00093-001

Figure 1. ADM8690

1.3V

LOW LINE

RESET

OSC IN

OSC SEL

TT ON

ADM8691/

ADM8695

4.65V

RESET AND

WATCHDOG

TIME BASE

RESET

GENERATOR

WATCHDOG

TRANSITION DETECTOR

WATCHDOG

TIMER

POWER-FAIL

INPUT (PFI)

WATCHDOG

INPUT (WDI)

BATT

OUT

POWER-FAIL

OUTPUT (PFO)

WATCHDOG

OUTPUT (WDO)

OUT

VOLTAGE DETECTOR = 4.65V

00093-002

Figure 2. ADM8691/ADM8695

ADM8690/ADM8691/ADM8695 Data Sheet

Rev. C | Page 2 of 24

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

Product Highlights ........................................................................... 1

Functional Block Diagrams ............................................................. 1

Revision History ............................................................................... 2

General Description ......................................................................... 3

Specifications ..................................................................................... 4 

Absolute Maximum Ratings ............................................................ 6

ESD Caution .................................................................................. 6

Pin Configurations and Function Descriptions ........................... 7

Typical Performance Characteristics ............................................. 9

Circuit Information ........................................................................ 11

Battery Switchover Section ........................................................ 11

Power-Fail

RESET

Output ......................................................... 11

Watchdog Timer

RESET

............................................................ 12

Watchdog Output (

WDO

) (ADM8691/ADM8695) ................. 13

Gating and RAM Write Protection

(ADM8691/ADM8695) ............................................................. 13



Power-Fail Warning Comparator ............................................. 14

Applications Information .............................................................. 15

Increasing the Drive Current .................................................... 15

Using a Rechargeable Battery for Backup ............................... 15

Adding Hysteresis to the Power-Fail Comparator ................. 15

Monitoring the Status of the Battery ....................................... 15

Alternate Watchdog Input Drive Circuits ............................... 16

Typical Applications ....................................................................... 17

ADM8690 Applications ............................................................. 17

ADM8691/ADM8695 Applications ......................................... 17

RESET

Output ............................................................................ 18

Power-Fail Detector ................................................................... 18

RAM Write Protection............................................................... 18

Watchdog Timer ......................................................................... 18

Outline Dimensions ....................................................................... 19

Ordering Guide .......................................................................... 22

REVISION HISTORY

12/11—Rev. B to Rev. C

Deleted ADM8692 and ADM8693 ............................. Throughout

Changes to Table 4 ............................................................................ 7

Change to Power-Fail

RESET

Output Section ............................ 11

Changes to ADM8691/ADM8695 Applications Section .......... 17

Updated Outline Dimensions ....................................................... 19

Changes to Ordering Guide .......................................................... 22

6/11—Rev. A to Rev. B

Deleted ADM8694 ......................................................... Throughout

Updated Figure 11, Figure 12, and Figure 13 ................................ 9

Updated Outline Dimensions ....................................................... 18

9/06—Rev. 0 to Rev. A

Updated Format .................................................................. Universal

Changes to Absolute Maximum Ratings ........................................ 6

Updated Ordering Guide .............................................................. 20

2/97—Revision 0: Initial Version

Data Sheet ADM8690/ADM8691/ADM8695

Rev. C | Page 3 of 24

GENERAL DESCRIPTION

The ADM8690/ADM8691/ADM8695 supervisory circuits offer

complete single-chip solutions for power supply monitoring and

battery control functions in microprocessor systems. These func-

tions include microprocessor reset, backup battery switchover,

watchdog timer, CMOS RAM write protection, and power failure

warning. The complete family provides a variety of configurations

to satisfy most microprocessor system requirements.

The ADM8690/ADM8691/ADM8695 are fabricated using an

advanced epitaxial CMOS process that combines low power

consumption (0.7 mW), extremely fast chip enable gating (3 ns),

and high reliability.

RESET

assertion is guaranteed with V

low as 1 V. In addition, the power switching circuitry is designed

for minimal voltage drop, thereby permitting increased output

current drive of up to 100 mA without the need for an external

pass transistor.

See Table 1 for a product selection guide listing the character-

istics of each device. To place an order, see the Ordering Guide.

Table 1. Product Selection Guide

Part No.

Nominal Reset

Time

Nominal V

Reset Threshold

Nominal Watchdog

Timeout Period

Battery Backup

Switching

Base Drive,

Ext PNP

Chip Enable

Signals

ADM8690 50 ms 4.65 V 1.6 sec Yes No No

ADM8691 50 ms or ADJ 4.65 V 100 ms, 1.6 sec, ADJ Yes Yes Yes

ADM8695 200 ms or ADJ 4.65 V 100 ms, 1.6 sec, ADJ Yes Yes Yes

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24

ADM8690ANZ

Mfr. #:

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