Power source equiment for power over ethernet system with increased cable length

Abstract

Increased cable length Power over Ethernet (PoE) systems are provided. Embodiments can be designed for compliance with IEEE 802.3af, IEEE 802.3at, or legacy PoE standards. Embodiments include PSE and PD designs enabled for increased length PoE. Embodiments include example modifications of IEEE 802.3af PSE system rules, including example modifications of PSE port voltage ranges to support IEEE 802.3af compliant PDs across increased cable lengths. Embodiments include example modifications of IEEE 802.3af PD system rules, including example modifications of PD port voltage ranges to enable current IEEE compliant PSEs to support increased cable length PoE. Embodiments include PDs having increased voltage process and/or added voltage protection circuitry to support increased length PoE. Modifications of PSE system rules and PD system rules can be performed independently of each others, so that modified PSEs can be made to work with existing PDs, or vice versa.

1 . A Power Source Equipment (PSE) for use in a Power over Ethernet (PoE) system, comprising:
 a DC voltage supply; and   a PSE controller;   wherein said PSE controller controls an output voltage of said DC voltage supply such that a voltage received at a powered device (PD) is in compliance with a PoE standard when said PD is connected to the said PSE via a cable that is at least approximately 100 meters long.   
   
   
       2 . The PSE of  claim 1 , wherein said cable is a CAT-5 cable. 
   
   
       3 . The PSE of  claim 1 , wherein said output voltage compensates for a voltage drop across said cable. 
   
   
       4 . The PSE of  claim 1 , wherein said PSE controller controls said output voltage of said DC voltage supply to have a minimum of approximately 16.95 volts during a classification phase and a minimum of approximately 64 volts after a startup phase, thereby enabling said cable to be up to approximately 350 meters long for an IEEE 802.3af compliant PD. 
   
   
       5 . The PSE of  claim 1 , wherein said PSE controller controls said output voltage of said DC voltage supply to have a minimum of approximately 18 volts during a classification phase and a minimum of approximately 76 volts after a startup phase, thereby enabling said cable to be up to approximately 500 meters long for an IEEE 802.3af compliant PD. 
   
   
       6 . The PSE of  claim 1 , wherein said voltage received at said PD complies with the IEEE 802.3af standard. 
   
   
       7 . The PSE of  claim 5 , wherein said voltage received at said PD has a minimum of approximately 36 volts and a maximum of approximately 57 volts after a startup phase. 
   
   
       8 . The PSE of  claim 1 , wherein said voltage received at said PD complies with the IEEE 802.3 at standard. 
   
   
       9 . The PSE of  claim 1 , wherein said voltage received at said PD complies with a legacy PD. 
   
   
       10 . The PSE of  claim 1 , wherein said DC voltage supply is capable of supplying at least approximately 76 volts. 
   
   
       11 . The PSE of  claim 1 , wherein said PSE controller:
 monitors an AC current over said cable; and   causes said DC voltage supply to stop supplying voltage when said AC current drops below a determined threshold for a determined duration.   
   
   
       12 . A Power over Ethernet (PoE) system, comprising:
 a power source equipment (PSE);   a powered device (PD); and   an Ethernet cable that connects said PSE and said PD and that is at least approximately 100 meters long;   wherein said PSE provides increased output voltage ranges to compensate for a maximum voltage drop across said Ethernet cable; and   wherein the PoE system is in compliance with at least one of the IEEE 802.3af standard, the IEEE 802.3af standard, and a legacy PoE standard.   
   
   
       13 . The PoE system of  claim 12 , wherein said cable is a CAT-5 cable. 
   
   
       14 . The PoE system of  claim 12 , wherein said PSE is capable of supplying at least approximately 15.4 Watts at said PD. 
   
   
       15 . The PoE system of  claim 12 , wherein said cable is approximately 350 meters long. 
   
   
       16 . The PoE system of  claim 12 , wherein said cable is approximately 500 meters long. 
   
   
       17 . A method for enabling an increased reach Power over Ethernet (PoE) system, comprising:
 determining the resistance of a cable connecting a Power Source Equipment (PSE) and a Powered Device (PD) of the PoE system; and   transmitting a voltage from said PSE to said PD, wherein said voltage compensates for said cable resistance and provides a minimum voltage of approximately 36 volts and a maximum voltage of approximately 57 volts at said PD after a startup phase, thereby complying with the IEEE 802.3af standard;   wherein said cable is at least approximately 100 meters long.   
   
   
       18 . The method of  claim 17 , wherein said voltage has a minimum of approximately 16.95 volts during a classification phase and minimum of approximately 64 volts after said startup phase, thereby enabling said cable to be up to approximately 350 meters long. 
   
   
       19 . The method of  claim 17 , wherein said voltage has a minimum of approximately 18 volts during a classification phase and a minimum of approximately 76 volts after said startup phase, thereby enabling said cable to be up to approximately 500 meters long.