Microprocessor Supervisory Circuits

________________________________________________________________

Maxim Integrated Products

1

1

2

3

4

8

7

6

5

RESET (RESET)

WDI

PFO

PFI

GND

DIP/SO

TOP VIEW

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L

( ) ARE FOR MAX805L ONLY.

_________________Pin Configurations

NMI

I/O LINE GND

CMOS

RAM

GND

UNREGULATED DC REGULATED +5V

RESET

PFO

WDI

GND

PFI

O.1

µF

3.6V

LITHIUM

BATTERY

MAX690A

MAX802L

µP

RESET

__________Typical Operating Circuit

Call toll free 1-800-998-8800 for free samples or literature.

19-4333; Rev 3; 9/93

__________________General Description

The MAX690A/MAX692A/MAX802L/MAX802M/MAX805L

reduce the complexity and number of components

required for power-supply monitoring and battery-control

functions in microprocessor (µP) systems. They signifi-

cantly improve system reliability and accuracy compared

to separate ICs or discrete components.

These parts provide four functions:

1) A reset output during power-up, power-down, and

brownout conditions.

2) Battery-backup switching for CMOS RAM, CMOS

µP, or other low-power logic.

3) A reset pulse if the optional watchdog timer has not

been toggled within 1.6sec.

4) A 1.25V threshold detector for power-fail warning or

low-battery detection, or to monitor a power supply

other than +5V.

The parts differ in their reset-voltage threshold levels

and reset outputs. The MAX690A/MAX802L/MAX805L

generate a reset pulse when the supply voltage drops

below 4.65V, and the MAX692A/MAX802M generate a

reset below 4.40V. The MAX802L/MAX802M guaran-

tee power-fail accuracies to ±2%. The MAX805L is the

same as the MAX690A except that RESET is provided

instead of RESET.

All parts are available in 8-pin DIP and SO packages.

The MAX690A/MAX802L are pin compatible with the

MAX690 and MAX694. The MAX692A/MAX802M are

pin compatible with the MAX692.

_______________________Applications

Battery-Powered Computers and Controllers

Intelligent Instruments

Automotive Systems

Critical µP Power Monitoring

___________________________Features

o Precision Supply-Voltage Monitor:

4.65V for MAX690A/MAX802L/MAX805L

4.40V for MAX692A/MAX802M

o Reset Time Delay – 200ms

o Watchdog Timer – 1.6sec Timeout

o Battery-Backup Power Switching

o 200µA Quiescent Supply Current

o 50nA Quiescent Supply Current in Battery-

Backup Mode

o Voltage Monitor for Power-Fail or Low-Battery

Warning

o Power-Fail Accuracy Guaranteed to ±2%

(MAX802L/M)

o Guaranteed

RESET Assertion to V

o 8-Pin SO and DIP Packages

______________Ordering Information

PART

TEMP. RANGE

PIN-PACKAGE

MAX690ACPA

8 Plastic DIP

MAX690ACSA

0°C to +70°C

8 SO

MAX690AC/D

0°C to +70°C

Dice*

MAX690AEPA

-40°C to +85°C

8 Plastic DIP

MAX690AESA

-40°C to +85°C

8 SO

MAX690AMJA

-55°C to +125°C

8 CERDIP**

Ordering Information continued on last page.

**Contact factory for availability and processing to MIL-STD-883.

0°C to +70°C