We use a ADUM1281 to isolate a CAN bus driver. The driver chip is a 82C251T. It usualy works fine, but at 1Mbit/s about once pr minute we have an error frame.
We have (with some difficulties) been able to catch the situation on an osciloscope. The magenta trace is the input to the isolator, and the yellow trace is the output from the same isolator channel. The yellow trace rises correctly about 30nS after the input. Then the input has a big ringing with the voltage dropping to ca 2V before rising again. 20nS after that, the output goes low. But it does not go high again. For the rest of the pulse, the input is high and the output low, which is clearly wrong. (The cyan trace is the TX signal and is not relevant here). Common mode voltage has been monitored, but is quite silent.
This looks for me like an internal hardware problem in the ADUM1281 isolator that is not documented in the datasheet. Both version A and C seems to have the same problem.