Specifications

PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Book 145
Power Line Power Supply Plus Coupler
One very convenient coupling circuit implementation combines an isolated universal-input power supply and a line-to-
neutral coupling circuit. Figure 4.26 illustrates how such a device is connected to a PL Smart Transceiver-based product.
The switch mode power supply inside the combined power supply/coupler provides power for the PL Smart Transceiver-
based product while the communication transformer couples the communication signal to the product over a common
pair of low-voltage wires. Inside the PL Smart Transceiver-based product the power and communication signals are
separated to perform their respective functions. Inductor L106 is used to prevent the low impedance of C103 from
shorting out the communication signal. Ferrite bead L102 has been added to ensure stability of the transmit amplifier
with the coupling transformer being remotely located from the PL Smart Transceiver. The particular ferrite bead that is
specified has been selected to have less or equal to 0.5 ohms of impedance at 100kHz so that a low value of transmit-
mode impedance is maintained at communication frequencies. Echelon Corporation sells both 5W and 10W versions of
this combined power supply plus coupler. Component values and part numbers for the circuitry to interface with this
power supply/coupler are given in example coupling circuit number 8 earlier in this chapter.
Figure 4.26 Power Line Power Supply Plus Coupler