1.The schematic diagram is as follows: the input voltage is about 8.4v, and the linear power supply is used for power supply; The load current is very small, less than 5mA.
2.The reference standard for surge test is GB / T 17626.5, common mode condition, and the test voltage is 2.8kv. There are similar problems under the condition of damped oscillation wave and ringing wave (common mode). The structure diagram of our product is as follows. There is no connection of common mode channel (separated by plastic shell). PCBA is placed in an insulating plastic shell with a whole piece of metal shell under it. The metal shell is grounded for common mode test.
3.Abnormal waveform will appear every time.