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]

A1: That's what I thought since brownout looks to be controlled by the same logic.

A2:

1: With the data we have the 3.4V was measured within a minute of the event. Not close enough, but it is doubtful the battery truly discharged below 2.7. A transient dip seems much more likely.

2: Absolutely IMHO. I'm an embedded FW guy, but that seems very likely. We'll see what the HW guys say.

3: We have a meeting in an hour or so. I strongly suspect a HW guy will get that action in the meeting

4: That's good to know. Nothing I read before suggested this.

5: Thanks for the suggestion. Plus the LPCOMP uses less power which is always a plus for us.