FUNCTIONAL BLOCK DIAGRAMS

1.3V

WATCHDOG

INPUT (WDI)

POWER FAIL

INPUT (PFI)

POWER FAIL

OUTPUT (PFO)

RESET

WATCHDOG

TIMER

BATT ON

OSC IN

OSC SEL

WATCHDOG

OUTPUT (WDO)

RESET

LOW LINE

RESET GENERATOR

TIMEBASE FOR RESET

AND WATCHDOG

WATCHDOG

TRANSITION DETECTOR

ADM696

1.3V

WATCHDOG

INPUT (WDI)

POWER FAIL

INPUT (PFI)

POWER FAIL

OUTPUT (PFO)

RESET

WATCHDOG

TIMER

OSC IN

OSC SEL

WATCHDOG

OUTPUT (WDO)

RESET

LOW LINE

RESET GENERATOR

TIMEBASE FOR RESET

AND WATCHDOG

WATCHDOG

TRANSITION DETECTOR

ADM697

REV. 0

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

Microprocessor

Supervisory Circuits

ADM696/ADM697

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

Tel: 617/329-4700

Fax: 617/326-8703

FEATURES

Superior Upgrade for MAX696/MAX697

Specified Over Temperature

Adjustable Low Line Voltage Monitor

Power OK/Reset Time Delay

Watchdog Timer—100 ms, 1.6 s, or Adjustable

Low Switch On Resistance

1.5

Normal, 20

in Backup

600 nA Standby Current

Automatic Battery Backup Switching (ADM696)

Fast On-Board Gating of Chip Enable Signals (ADM697)

Voltage Monitor for Power Fail or Low Battery Warning

APPLICATIONS

Microprocessor Systems

Computers

Controllers

Intelligent Instruments

Automotive Systems

Critical

P Power Monitoring

GENERAL DESCRIPTION

The ADM696/ADM697 supervisory circuits offer complete

single chip solutions for power supply monitoring and battery

control functions in microprocessor systems. These functions

include

µP reset, backup-battery switchover, watchdog timer,

CMOS RAM write protection, and power failure warning.

The ADM696/ADM697 are available in 16-pin DIP and small

outline packages and provide the following functions:

1. Power-On Reset output during power-up, power-down and

brownout conditions. The RESET voltage threshold is

adjustable using an external voltage divider. The RESET

2. A Reset pulse if the optional watchdog timer has not been

toggled within specified time.

3. Separate watchdog time-out and low line status outputs.

4. Adjustable reset and watchdog timeout periods.

5. A 1.3 V threshold detector for power fail warning, low bat-

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

processor or other low power logic (ADM696).

7. Write protection of CMOS RAM or EEPROM (ADM697).

The ADM696/ADM697 is fabricated using an advanced epitaxial

CMOS process combining low power consumption (5 mW),

extremely fast Chip Enable gating (5 ns) and high reliability.

RESET

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.