I am using an ADuM1201 to isolate a serial interface between grounded and line referenced circuits. Occasionally the output state of the grounded side output from the ADuM1201 (pin 2) goes into an open state, neither driving hi nor lo. The only way to get it out of the state is to remove the grounded side power and reapply the power - then it is happy again! I'm using 3.3V supplies and they are fine, no issue there.
Anybody else seen this, any ideas what is the cause (I know it's interference of some kind)?