Your observation was fully right.

Most internal watchdogs are tired in certain cases.

Thus for naming an internal watchdog useful, it must meet the following conditions:

1. it must already be enabled by power on reset

2. there exist no way to disable it by software

3. it must have a different clock source that it never sleeps, even if the CPU enters the power down state.


I use the MAX813L. For debugging or programming purposes it can be disabled by a jumper to let the trigger input floating. Then only the power on reset remain active.


Peter