Supervisor MPU Selection

Hi All,

I was wondering what the design considerations typically are for a microcontroller in regards to a supervisor IC. I'm using an 8051(Atmels 89S52) in a 5V system. I have noticed that it is possible for the micro to go crazy/fail with power glitches...noise and other disturbances to the power rails when using the standard RC for the POR.

Depending on the system I don't want to pick a voltage threshold too close to the power rails so when someone hooks up a long cable or for whatever reason voltage goes a few tenth's of a volt below 5 I don't want to have issues.(false resetting) On the flip side if I pick too low of a threshold and when voltage browns out the micro is still allowed to go crazy....any thoughts?

Thanks!

To look for a crash, typically you have the microcontroller generate a continuous pulse train on one of the pins as part of the normal software program loop and have a missing pulse detector watchdog circuit to check for missing pulses. If the pulses are missing, that is a sign that the controller has crashed and the circuit then resets it.