On to transient testing:
Positive spikes first. I used my bench power supply, set it to the wanted voltage, enabled it and then touched the positive output wire to the VOUT-pin. So there is the (smallish) output cap of the PSU charged to the set voltage and the contact bounce at play.
Lets see how my protection circuit mockup reacts to that.
I will start with the lower end of where the protection circuit reacts first. This is interesting because:
- the comparator reacts more slowly near to the threshold
- hysteresis issues would show up in this region if they are there
- the SMF5.0 TVS-diode that we added to VOUT_VREF could somehow interfere with the comparator threshold and cause oscillations
5.70V:
5.80V:
5.90V:
6.00V:
6.00V zoomed in to the first trigger:
As you can see there is some bouncing back and forth going on at the lower voltages. This gets less and less the higher you go - the comparator reacts faster then.
Does this look pretty? No.
Is it an issue? No.
The important part is that the protection is active at the end (gate low) and there is no constant oscillation going on. It always becomes stable after like 100ms.