How to suppress common-mode interference on the power side of a power DTU?

Suppressing common-mode interference on the power side of the DTU requires the deployment of common-mode filtering and shielding measures. A common-mode choke CML4532A-510T with an inductance of 51μH and an impedance greater than 500Ω at 1MHz should be installed at the power line inlet. A safety Y capacitor (2.2nF/250VAC) should be connected in parallel to ground. Shielded cables should be used for connection, with the shielding terminated 360 degrees to the metal casing. On the PCB, the power side area should be surrounded by a ground plane. Through simulation analysis of the common-mode rejection ratio (CMRR), filter parameters should be optimized to achieve a CMRR greater than 30dB. In actual measurements, conducted interference tests showed that common-mode interference in the 150kHz-30MHz frequency band should be below the EN55032 Class B limit. Suppressing common-mode interference can improve the system signal-to-noise ratio (SNR) by 20dB.