The system I am working on has ESD susceptibility issues. The communication channel between the host and the peripheral becomes disabled due to ESD events. I have found that I bring the PIN line (pin 12 on the ADUM4160) low using a pushbutton, the channel re-enumerates. I'd like to have the peripheral microcontroller do this and I'd like to know the minimum amount of time the PIN line needs to be brought low.
Applying low to PIN will remove power from the 1.5k upstream pull-up (on UD+ for full-speed, on UD- for low speed). There is the propagation delay for this input on side 2 to affect side…
I case nobody responds to this, 5 ms has been working.
Applying low to PIN will remove power from the 1.5k upstream pull-up (on UD+ for full-speed, on UD- for low speed). There is the propagation delay for this input on side 2 to affect side 1 (upstream); which isn't specified for ADuM4160, but this delay will be short compared to how long the pull-up must remain unpowered for the host to detect the condition as "unplugged" and then be ready to detect the ADuM4160 again once PIN is high.
5 ms may be too short for some hosts to detect the condition; you might want to consider the specific hosts (micros) you expect, but 10 ms or even longer might be a good idea to make sure the disconnect is detected. I recommend a search to see what's common for processor/software response times to an "unplug" event.
External ESD protection would be recommended for ADuM4160 in order to maintain normal operation, this might avoid the need to essentially power-cycle part of the upstream/port side of the ADuM4160.