How to isolate power supply noise from a concentrator?

High-frequency noise generated by the internal switching power supply of the concentrator can couple to sensitive acquisition and communication circuits through the power plane and ground plane, causing abrupt changes in the acquired data. The key to isolation is to employ multi-stage filtering and zoned power supply. A common-mode inductor CMZ1211-501T (500μH) and a Y capacitor (2.2nF) are used at the input of the AC/DC power module to suppress common-mode noise; a two-stage LC filter is added at the output, using a PBZ3216E120Z0T power inductor (12μH) and a low-ESR capacitor (470μF + 0.1μF). Independent LDO power supplies are provided for the analog acquisition circuit and the carrier communication circuit, such as using the TPS7A series, with a PBZ1608E600Z0T ferrite bead connected in series at its input. In the PCB layout, the switching power supply area is isolated from other circuits using slots, and power traces avoid crossing sensitive areas. Through noise isolation, the interference voltage of power supply noise on the acquisition circuit can be reduced to below 10mV, and the system conducted emissions meet the EN 55032 Class B limits.