3.3.3.3 PLC Coupling Circuit

The PLC coupling circuit connects the PLC signal directly to the mains grid or even to the 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 PL460-EK (see Figure 3-13) by a high voltage capacitor, C1. Resistors R10, R11 and R12 allow the high-voltage capacitor to discharge after disconnection from mains.

CAUTION: PLC coupling components are designed for a maximum voltage of 250 Vac or 325 Vdc.

The TR1 transformer (with turn ratio 1:1) provides safety isolation from the L-N connection.

Varistor, fuse and TVS diodes protect the board against overvoltages and high transient voltages (surges and spikes) from mains. For more information about TVS diode, SMAJ12CAE3 (D3), refer to the SMAJ12CAE3 product webpage.

Figure 3-13. Isolated Coupling Schematic