How to optimize the filtering of the power DTU communication loop?

Optimizing the DTU communication loop filtering requires customization based on the interface type and signal rate. For the RS485 interface, a TVS diode SMBJ6.5CA is connected in parallel to ground on both A/B lines, and a common-mode inductor CML3225A-510T is connected in series. The Ethernet interface uses an RJ45 connector with integrated filtering, which includes a common-mode choke and capacitor array. For high-speed serial ports, a low-capacitance π-type filter is used, employing a PBZ1608A-102Z0T ferrite bead and a 100pF capacitor. During optimization, signal integrity is verified through eye diagram testing to ensure that the rise time of the filtered signal meets protocol requirements. In actual testing, the bit error rate after filtering should be below 10^-9, and the immunity to interference should be improved to ±4kV EFT.