1

LTC692/LTC693

®

s

UL Recognized

s

s

1.5mA Maximum Supply Current

s

Fast (35ns Max.) On-Board Gating of RAM Chip

Enable Signals

s

SO8 and SO16 Packaging

s

4.40V Precision Voltage Monitor

s

Power OK/Reset Time Delay:

200ms or Adjustable

s

Minimum External Component Count

s

1

µA Maximum Standby Current

s

Voltage Monitor for Power Fail or

Low Battery Warning

s

Thermal Limiting

s

Performance Specified Over Temperature

s

Superior Upgrade for MAX690 Family

The LTC692/LTC693 provide complete power supply moni-

toring and battery control functions for microprocessor

reset, battery backup, CMOS RAM write protection, power

failure warning and watchdog timing. A precise internal

voltage reference and comparator circuit monitor the

power supply line. When an out-of-tolerance condition

occurs, the reset outputs are forced to active states and the

Chip Enable output unconditionally write-protects exter-

nal memory. In addition, the RESET output is guaranteed

The LTC692/LTC693 power the active CMOS RAMs with a

charge pumped NMOS power switch to achieve low drop-

out and low supply current. When primary power is lost,

auxiliary power, connected to the battery input pin, powers

the RAMs in standby through an efficient PMOS switch.

For an early warning of impending power failure, the

LTC692/LTC963 provide an internal comparator with a

user-defined threshold. An internal watchdog timer is

also available, which forces the reset pins to active states

when the watchdog input is not toggled prior to a preset

time-out period.

DESCRIPTIO

S

FEATURE

APPLICATI

TYPICAL

RESET Output Voltage vs

Supply Voltage

+

+

ADJ

10

µF

5V

100

µF

0.1

µF

µP NMI

µP

POWER

POWER TO

CMOS RAM

I/O LINE

µP RESET

µP

SYSTEM

0.1µF

3V

51k

10k

LTC692/3 • TA01

LT1086-5

MICROPROCESSOR RESET, BATTERY BACKUP, POWER FAILURE

WARNING AND WATCHDOG TIMING ARE ALL IN A SINGLE CHIP

FOR MICROPROCESSOR SYSTEMS.

LTC692

LTC693

PFI

WDI

RESET

PFO

GND

0.1

µF

100

Ω

Microprocessor

Supervisory Circuits

SUPPLY VOLTAGE (V)

0

3

4

5

4

2

1

0

1

2

3

5

EXTERNAL PULL-UP = 10µA

LTC692/3 • TA02

®

S

APPLICATI

s

Critical

µP Power Monitoring

s

Intelligent Instruments

s

Battery-Powered Computers and Controllers

s

Automotive Systems