Galvanic barrier coupler for intrinsically safe power over data line applications

A circuit for connection to a coaxial cable having a first conductor surrounded by a grounded sheath, the circuit comprising:

• a first transceiver having a first transmit terminal and a second transmit terminal for transmitting differential data signals over the first conductor, the first transceiver also having a first receive terminal and a second receive terminal for receiving the differential data signals over the first conductor;
• a first transformer having a first primary winding coupled across the first transmit terminal and the second transmit terminal of the first transceiver;
• and
• the first transformer having a first secondary winding having a first terminal coupled to a DC voltage source and having a second terminal configured to be coupled to the first conductor for providing a DC coupling between the DC voltage source and the first conductor,
• wherein the first transformer, via the first primary winding and the first secondary winding, provides the differential data signals output from the first transceiver to the first conductor, while a DC voltage from the DC voltage source is coupled to the first conductor via the first secondary winding.

A method performed by a circuit connected to a first conductor and a second conductor comprising:

• transmitting differential data signals over the first conductor and the second conductor by a first transceiver having a first transmit terminal and a second transmit terminal, the first transceiver also having a first receive terminal and a second receive terminal for receiving the differential data signals over the first conductor and the second conductor;
• applying the differential data signals across a primary winding of a first transformer, wherein the primary winding is coupled across the first transmit terminal and the second transmit terminal of the first transceiver,
• the first transformer having a first secondary winding having a first terminal coupled to a DC voltage source and having a second terminal coupled to the first conductor for providing a DC coupling between the DC voltage source and the first conductor,
• the first transformer having a second secondary winding having a third terminal coupled to the DC voltage source and having a fourth terminal configured to be coupled to the second conductor for providing a DC coupling between the DC voltage source and the second conductor;
• and
• generating the differential data signals on the first conductor and the second conductor, via the first secondary winding and the second secondary winding, and applying the differential data signals to the first conductor and the second conductor, while a DC voltage from the DC voltage source is coupled to the first conductor and the second conductor via the first secondary winding and the second secondary winding.