LTC692/LTC693

1

0692fb

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Microprocessor

Supervisory Circuits

n

Critical μP Power Monitoring

n

Intelligent Instruments

n

Battery-Powered Computers and Controllers

n

Automotive Systems

RESET Output Voltage vs

Supply Voltage

n

n

1.5mA Maximum Supply Current

n

Fast (35ns Maximum) Onboard Gating of RAM Chip

Enable Signals

n

4.40V Precision Voltage Monitor

n

Power OK/Reset Time Delay: 200ms or Adjustable

n

Minimum External Component Count

n

1μA Maximum Standby Current

n

Voltage Monitor for Power-Fail or Low Battery

Warning

n

Thermal Limiting

n

Performance Specified Over Temperature

n

Superior Upgrade for MAX690 Family

n

SO8 and SO16 Packaging

The LTC

monitoring and battery control functions for microproces-

sor 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 external

memory. In addition, the RESET output is guaranteed to

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/LTC693 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

timeout period.

ADJ

10μF

5V

100μF

0.1μF

μP NMI

μP

POWER

POWER TO

CMOS RAM

I/O LINE

μP RESET

μP

SYSTEM

0.1μF

3V

51k

10k

692_3 • TA01

LT1086-5

MICROPROCESSOR RESET, BATTERY BACKUP, POWER FAILURE

WARNING AND WATCHDOG TIMING ARE ALL IN A SINGLE CHIP

FOR MICROPROCESSOR SYSTEMS

GND

0.1μF

100Ω

+

+

LTC692

LTC693

PFI

WDI

RESET

PFO

SUPPLY VOLTAGE (V)

0

3

4

5

4

2

1

0

1

2

3

5

EXTERNAL PULL-UP = 10μA

692_3 • TA02

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