I use ADuM2401 for the isolation between the meter IC (Cirrus 5490 ; before the bridge diode) and secondary side MCU.
I found out that the Vdd1 (Secondary side) will pull down the 3.3V and cause the MCU shunt-down during the surge test (4KV, from AC inlet)
I removed the ADuM2401 and re-apply the surge test and the 3.3V works fine. Hence, I assume ADuM2401 Cause this fail.
Is there any way to solve this issue and what's the root cause of this issue ??
Hear from you soon and thank!!