Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Watchdog timer SOT 23 8

AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The MAX6369–MAX6374 are pin-selectable watchdog

timers that supervise microprocessor (µP) activity and

signal when a system is operating improperly. During

normal operation, the microprocessor should repeated-

ly toggle the watchdog input (WDI) before the selected

watchdog timeout period elapses to demonstrate that

the system is processing code properly. If the µP does

not provide a valid watchdog input transition before the

timeout period expires, the supervisor asserts a watch-

dog (WDO) output to signal that the system is not exe-

cuting the desired instructions within the expected time

frame. The watchdog output pulse can be used to reset

the µP or interrupt the system to warn of processing

errors.

The MAX6369–MAX6374 are flexible watchdog timer

supervisors that can increase system reliability through

notification of code execution errors. The family offers

several pin-selectable watchdog timing options to

match a wide range of system timing applications:

• Watchdog startup delay: provides an initial delay

before the watchdog timer is started.

• Watchdog timeout period: normal operating watch-

dog timeout period after the initial startup delay.

• Watchdog output/timing options: open drain (100ms)

or push-pull (1ms).

The MAX6369–MAX6374 operate over a +2.5V to +5.5V

supply range and are available in miniature 8-pin

SOT23 packages.

________________________Applications

Embedded Control Systems

Industrial Controllers

Critical µP and Microcontroller (µC) Monitoring

Automotive

Telecommunications

Networking

Features

o Precision Watchdog Timer for Critical

µP Applications

o Pin-Selectable Watchdog Timeout Periods

o Pin-Selectable Watchdog Startup Delay Periods

o Ability to Change Watchdog Timing Characteristics

Without Power Cycling

o Open-Drain or Push-Pull Pulsed Active-Low

Watchdog Output

o Watchdog Timer Disable Feature

o +2.5V to +5.5V Operating Voltage

o 8µA Low Supply Current

o No External Components Required

o Miniature 8-Pin SOT23 Package

Pin-Selectable Watchdog Timers

19-1676; Rev 5; 1/11

PART OUTPUT

WDO PULSE

WIDTH (ms)

MINIMUM STARTUP DELAY MINIMUM WATCHDOG TIMEOUT

MAX6369 Open Drain 100 Selectable: 1ms to 60s S el ectab l e: 1ms to 60s

MAX6370 Push-Pull 1 Selectable: 1ms to 60s S el ectab l e: 1ms to 60s

MAX6371 Open Drain 100 60s S el ectab l e: 1ms to 60s

MAX6372 Push-Pull 1 60s S el ectab l e: 1ms to 60s

MAX6373 Open Drain 100 S el ectab l e: 200µs to 60s or fi r st ed g eS el ectab l e: 30µs to 10s

MAX6374 Push-Pull 1 S el ectab l e: 200µs to 60s or fi r st ed g eS el ectab l e: 30µs to 10s

Selector Guide

PART

TEMP

RANGE

PIN-

PACKAGE

TOP

MARK

MAX6369KA-T

-40°C to +125°C

8 SOT23

AADC

MAX6369KA/V-T

-40°C to +125°C

8 SOT23

AEQV

MAX6369KA/V+T

-40°C to +125°C

8 SOT23

AEQV

MAX6370KA-T

-40°C to +125°C

8 SOT23

AADD

MAX6371KA-T

-40°C to +125°C

8 SOT23

AADE

MAX6372KA-T

-40°C to +125°C

8 SOT23

AADF

MAX6373KA-T

-40°C to +125°C

8 SOT23

AADG

MAX6374KA-T

-40°C to +125°C

8 SOT23

AADH

Ordering Information

Pin Configuration appears at end of data sheet.

Note: All devices are available in tape-and-reel only. Required

order increment is 2,500 pieces.

/V denotes an automotive qualified part.

Devices are available in both leaded and lead-free packaging.

Specify lead-free by replacing “-T” with “+T” when ordering.

MAX6369–MAX6374

Summary of content (10 pages)

PAGE 1
MAX6369–MAX6374 LE AVAILAB Pin-Selectable Watchdog Timers General Description The MAX6369–MAX6374 are pin-selectable watchdog timers that supervise microprocessor (µP) activity and signal when a system is operating improperly. During normal operation, the microprocessor should repeatedly toggle the watchdog input (WDI) before the selected watchdog timeout period elapses to demonstrate that the system is processing code properly.
PAGE 2
MAX6369–MAX6374 Pin-Selectable Watchdog Timers ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC .....................................................................-0.3V to +6V WDI.....................................................................-0.3V to +6V WDO (Open Drain: MAX6369/71/73) .................-0.3V to +6V WDO (Push-Pull: MAX6370/72/74 .......-0.3V to (VCC + 0.3V) SET0, SET1, SET2 ................................-0.3V to (VCC + 0.
PAGE 3
MAX6369–MAX6374 Pin-Selectable Watchdog Timers ELECTRICAL CHARACTERISTICS (continued) (VCC = +2.5V to +5.5V, SET_ = VCC or GND, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C and VCC = +3V.
PAGE 4
MAX6369–MAX6374 Pin-Selectable Watchdog Timers ELECTRICAL CHARACTERISTICS (continued) (VCC = +2.5V to +5.5V, SET_ = VCC or GND, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C and VCC = +3V.
PAGE 5
MAX6369–MAX6374 Pin-Selectable Watchdog Timers Pin Description PIN NAME FUNCTION 1 WDI Watchdog Input. If WDI remains either high or low for the duration of the watchdog timeout period (tWD), WDO triggers a pulse. The internal watchdog timer clears whenever a WDO is asserted or whenever WDI sees a rising or falling edge. 2 GND Ground 3 N.C. Not Connected. Do not make any connection to this pin. 4 SET0 Set Zero. Logic input for selecting startup delay and watchdog timeout periods.
PAGE 6
MAX6369–MAX6374 Pin-Selectable Watchdog Timers WDI VCC MAX6369–MAX6374 TRANSITION DETECTOR SET 2 CLEAR CONTROL LOGIC SET 1 EN ENABLE SET 0 SET WATCHDOG TIMEOUT OUT WDO OUTPUT SET STARTUP DELAY WATCHDOG TIMER CIRCUITRY GND Figure 1. Functional Diagram VCC tSETUP tDELAY tWD tWD tWD WDI A A B C E F D G E tWDO WDO A TRANSITIONS ON WDI IGNORED DURING SETUP DELAY. B TRANSITION(S) ON WDI IGNORED DURING STARTUP DELAY PERIOD.
PAGE 7
MAX6369–MAX6374 Pin-Selectable Watchdog Timers completion of the startup delay period, and no watchdog output pulses are asserted during the startup delay. When the startup delay expires, the watchdog begins counting its normal watchdog timeout period and waiting for WDI transitions. The startup delay allows time for the µP system to power up and fully initialize before assuming responsibility for the normal watchdog timer updates.
PAGE 8
MAX6369–MAX6374 Pin-Selectable Watchdog Timers Output START SET WDI HIGH PROGRAM CODE SUBROUTINE OR PROGRAM LOOP POSSIBLE INFINITE LOOP PATH SET WDI LOW The MAX6369/MAX6371/MAX6373 have an active-low, open-drain output that provides a watchdog output pulse of 100ms. This output structure sinks current when WDO is asserted. Connect a pullup resistor from WDO to any supply voltage up to +5.5V.
PAGE 9
MAX6369–MAX6374 Pin-Selectable Watchdog Timers Pin Configuration Chip Information TRANSISTOR COUNT: 1500 PROCESS: BiCMOS TOP VIEW WDI 1 GND 2 N.C. 3 SET0 4 MAX6369 MAX6370 MAX6371 MAX6372 MAX6373 MAX6374 SOT23 Maxim Integrated 8 VCC 7 WDO 6 SET2 5 SET1 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only.
PAGE 10
MAX6369–MAX6374 Pin-Selectable Watchdog Timers Revision History REVISION NUMBER REVISION DATE 0 1 4/00 7/00 Initial release Removed future product asterisk for MAX6370. 2 2/03 Corrected limits in Electrical Characteristics. 4 3 12/05 Added lead-free information to Ordering Information. 1 4 6/10 Revised the Ordering Information, Absolute Maximum Ratings, Electrical Characteristics, and the Selecting Device Timing section.