Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - system monitor Reset/power-on reset SOIC 8

LTC699

■

Guaranteed

Reset Assertion at V

= 1V

■

1.5mA Maximum Supply Current

■

SO-8 Packaging

■

4.65V Precision Voltage Monitor

■

Power OK/Reset Time Delay: 200ms

■

Minimum External Component Count

■

Performance Specified Over Temperature

■

Superior Upgrade for MAX699

The LTC699 provides power supply monitoring for

microprocessor-based systems. The features include mi-

croprocessor reset and watchdog timing. Precise internal

voltage reference and comparator circuit monitor the

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

occurs, the RESET output is forced to active low. In

addition, the RESET output is guaranteed to remain logic

low even with V

as low as 1V.

An internal watchdog timer is also available, which forces

the RESET output to active low when the watchdog input

is not toggled prior to the time-out period of 1.6 seconds.

The LTC699 is offered in DIP and surface mount packages.

ESCRIPTIO

Microprocessor

Supervisory Circuit

■

Critical µP Power Monitoring

■

Intelligent Instruments

■

Computers and Controllers

■

Automotive Systems

ITY

IDAGRA

0.1µF

µP POWER

I/O LINE

µP RESET

µP

SYSTEM

0.1µF

500k

LTC699 TA1

GND

WDI

RESET

MICROPROCESSOR RESET AND WATCHDOG TIMING IN

A SINGLE CHIP FOR MICROPROCESSOR SYSTEMS.

+5V

LTC699

RESET PULSE

GENERATOR

WDI

1.3V

–

OSC

RESET

LTC699 BD

GND

TRANSITION

DETECTOR

WATCHDOG

TIMER

Summary of content (4 pages)

PAGE 1
LTC699 Microprocessor Supervisory Circuit U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ Guaranteed Reset Assertion at VCC = 1V 1.5mA Maximum Supply Current SO-8 Packaging 4.65V Precision Voltage Monitor Power OK/Reset Time Delay: 200ms Minimum External Component Count Performance Specified Over Temperature Superior Upgrade for MAX699 The LTC699 provides power supply monitoring for microprocessor-based systems. The features include microprocessor reset and watchdog timing.
PAGE 2
LTC699 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Notes 1 and 2) Terminal Voltage VCC ................................................... –0.3V to 6.0V WDI Input .............................. – 0.3V to VCC + 0.3V RESET Output ...................................... – 0.3V to 6V Power Dissipation............................................. 500mW Operating Temperature Range LTC699C .............................................. 0°C to 70°C LTC699I .............................
PAGE 3
LTC699 U U U PI FU CTIO S VCC: +5V supply input. The VCC pin should be bypassed with a 0.1µF capacitor. GND: Ground pin. but not serviced prior to the time-out period, the reset pulse generator also forces RESET to active low for a minimum of 140ms for every time-out period (see Figure 2). RESET: Open drain output for µP reset control. When VCC falls below the reset voltage threshold (4.65V typically), RESET goes active low.
PAGE 4
LTC699 W U U UO APPLICATI S I FOR ATIO V2 V2 V1 VCC RESET V1 V1 = RESET VOLTAGE THRESHOLD V2 = RESET VOLTAGE THRESHOLD + RESET THRESHOLD HYSTERESIS t1 t1 t1 = RESET ACTIVE TIME LTC699 F01 Figure 1. Reset Active Time Watchdog Timer The LTC699 provides a watchdog timer function to monitor the activity of the microprocessor. If the microprocessor does not toggle the Watchdog Input (WDI) within the time-out period, RESET is forced to active low for a minimum of 140ms.