How should the bus port filtering of an intelligent controller (PAC) be designed?

The design of PAC bus port filtering for intelligent controllers needs to be customized according to the bus type and noise characteristics. For differential buses (such as USB and Ethernet), a common-mode inductor (CMZ2012A-900T) is placed at the port to suppress common-mode noise, and an ESD protection device (ESDLC5V0D3B) is connected in parallel. For single-ended buses (such as UART and I2C), a series ferrite bead (PBZ1608A-102Z0T) and a capacitor (such as 100pF) are connected in parallel to ground to form a low-pass filter. A π-type filter (inductor + capacitor) is added to the power pin. All filtering components should be placed close to the connector to ensure that noise is filtered out before entering the board. At the same time, the filter ground pin is directly connected to the independent copper area of the interface ground, which is connected to the chassis through a low-impedance path. Tests have verified that this filtering design can reduce conducted interference at the bus port by 25dB in the 150kHz-30MHz range, pass the IEC61000-4-4 EFT 4kV test, and achieve a 100% signal integrity eye diagram pass rate.