How to rectify EMC issues related to packet loss during data upload from power FTUs?

EMC rectification of data upload packet loss identified the source of interference and enhanced protection.

First, the source was identified: The communication line waveform was monitored with an oscilloscope to determine whether the interference was conducted (waveform glitches) or radiated (overall waveform rise).

Rectification measures: For conducted interference, a common-mode inductor CMZ3225A-510T and a TVS diode SMBJ6.5CA were added; for radiated interference, shielding was strengthened, such as replacing the cable with better shielded cable and adding a ferrite core at the interface.

Software measures: A retransmission mechanism and CRC check were added.

PCB rectification: Grounding continuity was checked, and power supply decoupling was strengthened.

Through these rectifications, the packet loss rate was reduced from 1% to 0.001%, meeting the IEC 61000-4-4 EFT 4kV test requirements.