POF warning question

[John]

Hello,

This is a quick question regarding the behavior of the Power Supervisor POF warning. We implemented a fairly naive use of the POF warning where we would log an POF event whenever we received a POF warning. We set the POF warning threshold to 2.7V. After seeing the event when we didn't expect it, we added some debug to log a very recent battery voltage measurement to our log when we logged the POF warning. It showed the battery voltage to be 3.4V.

This led to a number of questions regarding how the POF works. Most of which I could answer based on the reference manual and questions and responses on the forum. However, there were two questions I could not answer.

One, was how long a duration of the voltage below 2.7V is needed to trigger the POF warning. My guess based on what I see in the reference manual is any transient below 2.7V will trigger the warning (assuming of course that the voltage went back above the hysteresis level after each trigger). Is this correct, or does the voltage need to remain below 2.7V for some small amount of time before the warning is triggered?

Two, was is it possible to see false triggers of the POF warning?

Thanks, John

[John]

Also note, we are making an addtional change to our implementation. We are adding a battery measurement to the event handler rather than using the last measurement made. We are also looking at checking the battery voltage via a timer some short time after the event before taking any action to shut down gracefully. 2.7V actually provides us with quite a bit of margin unless we have something like a short on the board.