3.3.5.3 PLC Coupling Circuit

PLC coupling circuit connects the PLC signal directly to the mains grid or even to DC power rails without requiring any hardware adaptation. The main purpose of the circuit is to block the mains voltage of the grid to/from which the signal is injected/received. This is carried out in PL360G55CF-EK, see Figure 3-11, by a high voltage capacitor, C101. Resistors R107, R110 and R112 allow the high voltage capacitor to discharge after disconnection from mains.

CAUTION: PLC coupling components are designed for a maximum voltage of 230 V_AC or 200 V_DC.

The TR100 transformer (with turn ratio 1:1) provides galvanic isolation from mains. A non-isolated version could easily be implemented removing TR100, soldering R105 and R115 resistors and updating the value of L103 and R109 according to the PLCOUP011-NONISO design.

MOV100 varistor, F100 fuse and D102 TVS diode protect the coupling circuit from overvoltages and high transient voltages (surges and spikes) from mains.