Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Watchdog timer SC 70 5

General Description

The MAX6814 is a low-power watchdog circuit in a

tiny 5-pin SC70 package. This device improves system

reliability by monitoring the system for software code

execution errors. When the watchdog input detects a

transitional edge, the internal watchdog timer clears and

restarts, then begins counting again. If the watchdog

timer exceeds the watchdog timeout period (1.6s typ),

the active-low, push-pull watchdog output asserts for the

watchdog pulse period (140ms min) to alert the system

of the fault.

The MAX6814 consumes only 4µA of supply current and

is fully specified over the extended temperature range.

Applications

● Computers and Controllers

● Embedded Controllers

● Intelligent Instruments

● Critical µP Monitoring

Features

● 4µA Operating Current

● Watchdog Timer with 1.6s Timeout

● 140ms (min) WDO Pulse Period

● Push-Pull Active-Low WDO

● Fully Specified Over Extended Temperature Range

● No External Components

Devices are available in both leaded and lead(Pb)-free/RoHS-

compliant packaging. Specify lead-free by replacing “-T” with

“+T” when ordering.

PART

TEMP

RANGE

PIN-

PACKAGE

TOP

MARK

MAX6814XK-T -40°C to +85°C 5 SC70 AEK

GND

WDI

MAX6814

SC70-5

TOP VIEW

N.C.

WDO

MAX6814

µP

GND

NMI

I/O

WDO

WDI

MAX6814 5-Pin Watchdog Timer Circuit

19-2804; Rev 3; 7/14

Pin CongurationTypical Operating Circuit

Ordering Information

Summary of content (6 pages)

PAGE 1
MAX6814 5-Pin Watchdog Timer Circuit General Description The MAX6814 is a low-power watchdog circuit in a tiny 5-pin SC70 package. This device improves system reliability by monitoring the system for software code execution errors. When the watchdog input detects a transitional edge, the internal watchdog timer clears and restarts, then begins counting again. If the watchdog timer exceeds the watchdog timeout period (1.
PAGE 2
MAX6814 5-Pin Watchdog Timer Circuit Absolute Maximum Ratings VCC........................................................................-0.3V to +6.0V All Other Pins............................................ -0.3V to (VCC + 0.3V) Input Current, WDI..............................................................20mA Output Current, WDO..........................................................20mA Continuous Power Dissipation (TA = +70°C) 5-Pin SC70 (derate 3.1mW/°C above +70°C)..............
PAGE 3
MAX6814 5-Pin Watchdog Timer Circuit Typical Operating Characteristics (VCC = +5V, TA = +25°C, unless otherwise noted.) 7 6 5 4 3 2 230 220 210 200 190 180 170 160 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 150 WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE 2.0 MAX6814 toc03 MAX6814 toc02 240 WDO PULSE PERIOD (ms) SUPPLY CURRENT (mA) 8 1 250 MAX6814 toc01 9 WDO PULSE PERIOD vs. TEMPERATURE WATCHDOG TIMEOUT PERIOD (s) VCC SUPPLY CURRENT vs. TEMPERATURE 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.
PAGE 4
MAX6814 5-Pin Watchdog Timer Circuit MAX6814 VCC WDO PULSE GENERATOR UVLO WDI WATCHDOG TRANSITION DETECTOR WDO WATCHDOG TIMER GND Figure 1. Functional Diagram Detailed Description Applications Information Watchdog Input Watchdog Input Current In the MAX6814, the watchdog circuit monitors the µP’s activity. If the µP does not toggle the watchdog input (WDI) within tWD (1.6s), WDO asserts. The internal 1.
PAGE 5
MAX6814 5-Pin Watchdog Timer Circuit Watchdog Software Considerations One way to help the watchdog timer monitor software execution more closely is to set and clear the watchdog input at different points in the program, rather than pulsing the watchdog input high-low-high or lowhigh-low. This technique avoids a stuck loop, in which the watchdog timer would continue to be cleared inside the loop, keeping the watchdog from timing out.
PAGE 6
MAX6814 5-Pin Watchdog Timer Circuit Revision History REVISION NUMBER REVISION DATE 3 7/14 PAGES CHANGED DESCRIPTION No /V OPNs; removed Automotive reference from Applications section 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product.