Power-over-ethernet (PoE) device with multi-output transformer to generate output PoE power and device operational power
A power-over-Ethernet (PoE) PD/PSE device comprises a powered device (PD) interface configured to connect to an upstream power sourcing equipment (PSE) and receive input PoE power from the PSE, and a PSE interface configured to connect to a downstream PD and to supply output PoE power to the PD. The PD/PSE also comprises a device power rail to supply operational power to one or more components of the PD/PSE, and a DC-DC converter comprising a multi-output transformer comprising a transformer input, a first transformer output electrically connected to the PSE interface, and a second transformer output electrically connected to the device power rail. The DC-DC converter is configured to receive the input PoE power and, in response, supply the input PoE power to the transformer input, generate the output PoE power at the first transformer output, and generate the operational power at the second transformer output.
1 . A hybrid powered device/power sourcing equipment (PD/PSE), comprising:
a powered device (PD) interface configured to removably receive a connector of an ethernet cable to communicably connect the PD/PSE to an upstream power sourcing equipment (PSE) and receive input power-over-Ethernet (POE) power from the PSE;
a PSE interface configured to removably receive another connector of another ethernet cable to communicably connect the PD/PSE to a downstream PD and to supply output PoE power to the PD;
a device power rail to supply operational power to one or more components of the PD/PSE; and
a DC-DC converter comprising a multi-output transformer comprising a transformer input, a first transformer output electrically connected to the PSE interface, and a second transformer output electrically connected to the device power rail,
wherein DC-DC converter is configured to receive the input PoE power and, in response, supply the input PoE power to the transformer input, generate the output PoE power at the first transformer output, and generate the operational power at the second transformer output and supply the operational power from the second transformer output to the device power rail.
2 . The PD/PSE of claim 1 ,
wherein the DC-DC converter is configured to monitor the output PoE power generated at the second transformer output and to adjust a gain of the DC-DC converter based on the output PoE power.
3 . The PD/PSE of claim 2 ,
wherein the DC-DC converter comprises switching circuitry configured to supply the input PoE power to the transformer input in pulses at a duty cycle; and
wherein the DC-DC converter is configured to adjust the gain by adjusting the duty cycle.
4 . The PD/PSE of claim 3 ,
wherein the switching circuitry comprises:
a switch configured to supply the input power to the transformer input according to the duty cycle; and
a pulse-width-modulation (PWM) controller configured to control the duty cycle by supplying a PWM signal to a control terminal of the switch.
5 . The PD/PSE of claim 4 ,
wherein the PWM controller is configured to control the duty cycle based on the output PoE power such that the output PoE power is maintained at a predetermined target voltage or within a predetermined target voltage range.
6 . The PD/PSE of claim 5 , comprising:
wherein the predetermined target voltage is 54V and a turns ratio of primary windings to first secondary windings is N p /N s1 =0.5, where the primary windings are associated with the transformer input and the first secondary windings are associated with the first transformer output.
7 . The PD/PSE of claim 6 , comprising:
wherein a turns ratio of the primary windings to second secondary windings is N p /N s2 =2.25, where second secondary windings are associated with the second transformer output.
8 . The PD/PSE of claim 4 , comprising:
voltage measurement and feedback circuitry configured to measure the voltage of the output PoE power generated at the second transformer and feedback information indicative of the measured voltage to the PWM controller.
9 . The PD/PSE of claim 1 , comprising:
a DC power port configured to receive input DC power from an external power source, and
wherein DC-DC converter is configured to receive the input DC power and, in response, supply the input DC power to the transformer input, generate the output PoE power at the first transformer output, and generate the operational power at the second transformer output.
10 . The PD/PSE of claim 1 , comprising:
a PD chip configured to receive the input PoE power from the PD interface and supply the input PoE power to the DC-DC converter.
11 . The PD/PSE of claim 1 , comprising:
a PSE chip configured to receive the output PoE power from the first transformer output and supply the output PoE power to the PSE interface.
12 . The PD/PSE of claim 1 ,
wherein the DC-DC converter comprises switching circuitry configured to supply the input PoE power to the transformer input in pulses at a duty cycle,
wherein the DC-DC converter is configured to control a gain of the DC-DC converter for both the output PoE Power and the operational power by adjusting the duty cycle based on the voltage of the output PoE power and without regard to the voltage of the operational power.
13 . A system comprising:
the PD/PSE of claim 1 ;
the upstream PSE connected to the PD/PSE by a first ethernet cable connected to the PD interface;
the downstream PD connected to the PD/PSE by a second ethernet cable connected to the PSE interface;
wherein the PSE is configured to supply the input PoE power to the PD/PSE, and
wherein the PD/PSE is configured to supply the output PoE power to the PD.
14 . A system comprising:
the PD/PSE of claim 9 , wherein the external power source is connected to the DC power port to supply the input DC power;
the downstream PD connected to the PD/PSE by an ethernet cable connected to the PSE interface;
wherein the PD/PSE is configured to supply the output PoE power to the PD.
15 . A method comprising:
receiving input power at a hybrid powered device/power sourcing equipment (PD/PSE);
directing the received input power to a DC-DC converter comprising a multi-output transformer;
converting, by the DC-DC converter, the input power into at least two output power signals including:
a PoE output power signal generated at a first transformer output of the transformer; and
an operational power signal generated at a second transformer output of the transformer;
supplying the output PoE power from the first transformer output to a PSE port of the PD/PSE; and
supplying the operational power signal from the second transformer output to a device power rail of the PD/PSE.
16 . The method of claim 15 , comprising:
monitoring the output PoE power; and
controlling a gain of the DC-DC converter based on the output PoE power.
17 . The method of claim 16 ,
wherein controlling the gain comprises controlling a duty cycle of switching circuitry which supplies the input power to the transformer in pulses such that the voltage of the output PoE power is maintained at a predetermined target voltage or within a predetermined target range.
18 . The method of claim 15 ,
wherein the input power comprises input PoE power received from an upstream PSE.
19 . The method of claim 15 ,
wherein the input power comprises input DC power received from an external power source.
20 . The method of claim 15 ,
supplying the output PoE power from the PSE port of the PD/PSE to a downstream PD connected to the PSE port by an ethernet cable.