How to rectify the non-compliance of conducted emission from a power FTU?

Conducted emissions non-compliant, requiring rectification to locate the interference source and strengthen filtering.

Location: Use a near-field probe to scan the PCB to identify the noise source (e.g., switching power supply, clock circuit).

Rectification measures: Add a CMZ7060A-701T common-mode inductor to the power input; add RC snubber to the switching power supply MOSFET; add a PBZ1608E600Z0T ferrite bead in series for the clock signal.

PCB rectification: Check grounding continuity; add grounding to sensitive lines; place decoupling capacitors close to the IC.

Cable rectification: Use shielded cables, grounding the shielding layer.

After rectification, conducted emissions in the 150kHz-30MHz frequency band are more than 10dB below the limit, meeting GB/T 9254 Class B requirements.