We are developing with AD8422ARMZ in amps and have noticed what looks like a latch-up issue with "balanced" positive and negative rails. The only discernible symptom of the problem is that the input terminals go to one of the rails. Since reading the PCN, we have identified that the batch of ICs we are developing with fails within the effectivity date.
Our remedial action so far has been to replace the ICs within the effectivity date with samples outside the effectivity date (date code 1551) and so far this has proved to be a successful remedy. The slightly concerning issue is that this has occurred very repeatedly on all our chips and occurs with the inputs tied to functional ground via low impedance (so not just at high impedance as indicated on the PCN).
My questions are: