How should the power supply filtering of a concentrator be designed?

The concentrator power supply filtering design must simultaneously meet conducted emission (CE) standards and internal noise immunity requirements, employing a multi-stage architecture.

The first stage is the AC input, using a common-mode inductor CMZ1211-501T (500μH) and a Y capacitor (2.2nF/Y1) to filter common-mode noise, and an X capacitor (0.22μF/X2) and a differential-mode inductor PBZ3216E120Z0T (12μH) to filter differential-mode noise.

The second stage is before the DC/DC module input, adding a π-type filter composed of a ferrite bead PBZ1608E600Z0T and a capacitor (100μF + 0.1μF).

The third stage is for local power supply filtering of various functional circuits (such as the MCU and carrier chip), using ferrite beads (e.g., PBZ1005B-501Z0T) and decoupling capacitors (10μF + 0.1μF).

All filtering circuits should be located close to the power input or chip pins, with the ground terminal directly connected to a complete ground plane. This filtering design enables the concentrator to operate 10 dB below the limit in conducted emissions tests from 0.15 to 30 MHz and to withstand IEC 61000-4-4 EFT 4kV interference.