Power coupling circuits for single-pair ethernet with automotive applications

1. A circuit for power over data line (PoDL) injection, the circuit comprising:

a power source configured to provide one or more DC voltage levels;

a first coupling component configured to couple the power source to an interface for coupling to a transmission medium; and

an Ethernet device coupled through a second coupling component to the interface,

wherein:

the first coupling component is a balanced component, and

the Ethernet device is isolated from the power source via a pair of DC blocking capacitors, wherein the pair of DC blocking capacitors are separate from the first coupling component and are connected between the first coupling component and the second coupling component.

2. The circuit of claim 1 , wherein the first coupling component comprises a pair of matched inductors, and wherein matching between the pair of matched inductors is achieved over a frequency and temperature range of interest and with a predetermined DC voltage level.

3. The circuit of claim 1 , wherein the second coupling component comprises a common-mode choke (CMC) coupled at first terminals to the Ethernet device and at second terminals to the pair of DC blocking capacitors.

4. The circuit of claim 1 , wherein the transmission medium comprises one of a shielded twisted pair (STP) or an unshielded twisted pair (UTP) cable, and wherein the interface comprises a medium independent interface (MDI) port.

5. The circuit of claim 1 , wherein the interface is terminated using a pair of common mode (CM) terminations, each CM termination comprising a resistor connected in series with a capacitor coupled to ground potential.

6. The circuit of claim 1 , wherein the Ethernet device comprises an Ethernet physical (PHY) device.

7. The circuit of claim 1 , wherein the Ethernet device is powered by the power source through a path other than through the first coupling component, and wherein the one or more DC voltage levels comprise 12 Volt (V), 24V, and 48V.

8. The circuit of claim 1 , wherein the transmission medium transmits DC power of the power source and data to another Ethernet device, wherein the another Ethernet device comprises an Ethernet physical (PHY) device.

9. A circuit for power over data line (PoDL) injection, the circuit comprising:

a power source configured to provide one or more DC voltage levels;

a first coupling component configured to couple the power source to a second coupling component;

an interface for coupling to a transmission medium, the interface coupled through the second coupling component and the first coupling component to the power source; and

an Ethernet device coupled through the second coupling component to the interface, wherein:

the Ethernet device is isolated from the power source via a pair of DC coupling capacitors, and the second coupling component is configured to attenuate common mode (CM) noise.

10. The circuit of claim 9 , wherein the first coupling component comprises a pair of inductors, and wherein the second coupling component is configured to prevent mismatching between the pair of inductors from affecting noise immunity and electromagnetic compatibility (EMC).

11. The circuit of claim 9 , wherein the second coupling component comprises a common-mode choke (CMC) coupled at first terminals to the pair of DC blocking capacitors and at second terminal to the interface.

12. The circuit of claim 9 , wherein the transmission medium comprises one of a shielded twisted pair (STP) or an unshielded twisted pair (UTP) cable, and wherein the interface comprises a medium independent interface (MDI) port.

13. The circuit of claim 9 , wherein the interface is terminated using a pair of common mode (CM) terminations, each CM termination comprising a resistor connected in series with a capacitor coupled to ground potential.

14. The circuit of claim 9 , wherein the Ethernet device comprises an Ethernet physical (PHY) device.

15. The circuit of claim 9 , wherein the Ethernet device is powered by the power source through a path other than through the first coupling component, and wherein the one or more DC voltage levels comprise 12 Volt (V), 24V, and 48V.

16. The circuit of claim 9 , wherein the transmission medium transmits DC power of the power source and data to another Ethernet device, wherein the another Ethernet device comprises an Ethernet physical (PHY) device.

17. A circuit for power over data line (PoDL) injection, the circuit comprising:

a power source configured to provide one or more DC voltage levels;

a first coupling component configured to couple the power source to an interface; and

an Ethernet device coupled through a second coupling component to the interface,

wherein:

the Ethernet device is isolated from the power source through at least the second coupling component, and

the interface comprises a medium independent interface (MDI) port.

18. The circuit of claim 17 , wherein:

the first coupling component comprises a single inductor, and

the second coupling component comprises a balun transformer.

19. The circuit of claim 17 , wherein:

the second coupling component comprises a balun transformer with a middle tap on a secondary winding ,

the first coupling component comprises a short circuit connecting a power node of the power source to the middle tap of the balun transformer,

the interface comprises a medium independent interface (MDI) port.

20. The circuit of claim 17 , wherein:

the second coupling component comprises a common-mode choke (CMC) coupled through a pair of blocking capacitors and an auto-transformer to the interface,

the first coupling component comprises a short circuit connecting the power node of the power source to a middle tap of the auto-transformer, and

the interface comprises a medium independent interface (MDI) port.