Applications Information

Power Supply Bypassing

Watchdog Software Considerations

To help the watchdog timer monitor software execution more closely, set and reset the watchdog input at different points

in the program, rather than pulsing the watchdog input high-low-high or low-high-low. This technique avoids a stuck loop,

in which the watchdog timer would continue to be reset inside the loop, keeping the watchdog from timing out. Figure 6

shows an example of a flow diagram where the I/O driving the watchdog input is set high at the beginning of the program,

set low at the end of every subroutine or loop, then set high again when the program returns to the beginning. If the

program should hang in any subroutine, the problem would be quickly corrected, since the I/O is continually set low and

the watchdog timer is allowed to time out, causing WDO to pulse.

START

SET WDI

HIGH

PROGRAM

CODE

SUBROUTINE OR

PROGRAM LOOP

SET WDI LOW

RETURN

POSSIBLE INFINITE

LOOP PTH

Figure 6. Watchdog Flow Diagram

The

MAX16152/MAX16153/MAX16154/MAX16155

are relatively

immune

to

short-duration

negative-going

Typical Operating Characteristics show Maximum Transient Duration vs. Reset Threshold Overdrive, for which reset

MAX16152/MAX16153/

MAX16154/MAX16155

nanoPower Supervisor and Watchdog Timer

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