AC Disconnect of Power Over Ethernet Devices

Abstract

Embodiments of power sourcing equipment (PSE) utilizing AC disconnect are provided herein. In one embodiment, a PSE is provided that includes a DC supply configured to provide a DC voltage over a data communications medium, a controller configured to provide an AC disconnect signal over the data communications medium, and a parallel inductor-capacitor (LC) circuit coupled between the DC supply and the data communications medium. The parallel LC circuit is configured to isolate the DC supply from the AC disconnect signal. In another embodiment, a PSE is provided that includes a DC supply configured to provide a DC voltage at an output, an inductor coupled between the output of the DC supply and a data communications medium, and a capacitor coupled between the data communications medium and ground. The inductor and capacitor form a series LC circuit configured to generate an AC disconnect signal.

What is claimed is: 
     
         1 . Power sourcing equipment (PSE) for providing DC power to a powered device (PD) over a data communications medium, the PSE comprising:
 a DC supply configured to provide a DC voltage over the data communications medium;   a controller configured to provide an AC disconnect signal over the data communications medium; and   a parallel inductor-capacitor (LC) circuit coupled between the DC supply and the data communications medium, the parallel LC circuit configured to isolate the DC supply from the AC disconnect signal.   
     
     
         2 . The PSE of  claim 1 , wherein the parallel LC circuit has an associated resonant frequency that is substantially equal to a frequency of the AC disconnect signal. 
     
     
         3 . The PSE of  claim 2 , wherein the frequency of the AC disconnect signal is a fundamental frequency of the AC disconnect signal. 
     
     
         4 . The PSE of  claim 1 , wherein data is transmitted concurrently with the DC power over the data communications medium. 
     
     
         5 . The PSE of  claim 4 , wherein the data is transmitted in accordance with the IEEE 802.3 standard. 
     
     
         6 . The PSE of  claim 1 , wherein the controller further comprises:
 a charge pump coupled to the DC supply and configured to provided an output voltage greater than the DC voltage provided by the DC power supply; and   a switch configured to intermittently couple the output voltage of the charge pump to the data communications medium to provide the AC disconnect signal.   
     
     
         7 . Power sourcing equipment (PSE) for providing DC power to a powered device (PD) over spare wires of a data communications medium, the PSE comprising:
 a DC supply configured to provide a DC voltage over the spare wires of the data communications medium;   a controller configured to provide an AC disconnect signal over the spare wires of the data communications medium; and   a parallel inductor-capacitor (LC) circuit coupled between the DC supply and the spare wires of the data communications medium, the parallel LC circuit configured to isolate the DC supply from the AC disconnect signal.   
     
     
         8 . The PSE of  claim 7 , wherein the parallel LC circuit has an associated resonant frequency that is substantially equal to a frequency of the AC disconnect signal. 
     
     
         9 . The PSE of  claim 8 , wherein the frequency of the AC disconnect signal is a fundamental frequency of the AC disconnect signal. 
     
     
         10 . The PSE of  claim 7 , wherein data is transmitted in accordance with the IEEE 802.3 standard over the data communications medium. 
     
     
         11 . The PSE of  claim 7 , wherein the controller further comprises:
 a charge pump coupled to the DC supply and configured to provided an output voltage greater than the DC voltage provided by the DC power supply; and   a switch configured to intermittently couple the output voltage of the charge pump to the spare wires of the data communications medium to provide the AC disconnect signal.   
     
     
         12 . Power sourcing equipment (PSE) for providing DC power to a powered device (PD) over a data communications medium, the PSE comprising:
 a DC supply configured to provide a DC voltage at an output;   an inductor coupled between the output of the DC supply and the data communications medium; and   a capacitor coupled between the data communications medium and ground,   wherein the inductor and capacitor form a series inductor-capacitor (LC) circuit configured to generate an AC disconnect signal.   
     
     
         13 . The PSE of  claim 12 , wherein the series LC circuit is configured to generate the AC disconnect signal if the PD is disconnected from the data communications medium. 
     
     
         14 . The PSE of  claim 12 , wherein the series inductor-capacitor (LC) circuit forms a tank circuit. 
     
     
         15 . The PSE of  claim 12 , wherein the AC disconnect signal has a frequency substantially equal to the resonant frequency of the series LC circuit. 
     
     
         16 . Power sourcing equipment (PSE) for providing DC power to a powered device (PD) over spare wires of a data communications medium, the PSE comprising:
 a DC supply configured to provide a DC voltage at an output;   an inductor coupled between the output of the DC supply and the spare wires of the data communications medium; and   a capacitor coupled between the spare wires of the data communications medium and ground,   wherein the inductor and capacitor form a series inductor-capacitor (LC) circuit configured to generate an AC disconnect signal.   
     
     
         17 . The PSE of  claim 16 , wherein the series LC circuit is configured to generate the AC disconnect signal if the PD is disconnected from the data communications medium. 
     
     
         18 . The PSE of  claim 16 , wherein the series inductor-capacitor (LC) circuit forms a tank circuit. 
     
     
         19 . The PSE of  claim 16 , wherein the AC disconnect signal has a frequency substantially equal to the resonant frequency of the series LC circuit.