Method and apparatus for supplying power in a local area network

• US 20050041800A1
• Filed: 09/27/2004
• Published: 02/24/2005
• Est. Priority Date: 01/12/1999
• Status: Active Grant

• Current Assignee: Microsemi Corp. - Analog Mixed Signal Group, Ltd. (Microchip Technology Incorporated)
• Original Assignee: Microsemi Corp. - Analog Mixed Signal Group, Ltd. (Microchip Technology Incorporated)
• Inventors: Pincu, David, Korcharz, Dror, Lehr, Amir, Atias, Ilan
• Granted Patent: US 7,437,217 B2
• Time in Patent Office: Days
• US Class Current: 379/413
• CPC Class Codes: G05F 1/66 Regulating electric power
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/3287 by switching off individual functional units in the computer system
• CPC Class Codes: H02G 3/00 Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles installations of bus-bars H02G5/00; overhead installations H02G7/00; installations in or on the ground H02G9/00
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 12/44 Star or tree networks
• CPC Class Codes: H04L 69/323 in the physical layer [OSI layer 1]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04M 19/08 with current supply sources at the substations generating ringing current H04M19/04

Abstract

A method for supplying power to a local area network node over communication cabling, the method comprising: injecting current-limited current into communication cabling connected to the local area network node; measuring a voltage developed in accordance with said injected current limited current across said communication cabling at three pre-determined intervals; and determining, as a consequence of said measured voltage at said three pre-determined intervals whether characteristics of the local area network node allow it to receive power over the communication cabling.

Claims

1. A power supply subsystem for providing electrical power to a local area network node over communication cabling, the power supply subsystem comprising:

a power management and control unit;

current limiting circuitry responsive to said power management and control unit to provide a current limited output;

voltage measurement means; and

at least one of a combiner and a power supply interface operative to couple said current limited output to the communication cabling;

said power management and control unit being further operative to;

measure, utilizing said voltage measuring means at three pre-determined intervals, a voltage developed in accordance with said coupled current limited output; and

determine, as a consequence of said measured voltage whether characteristics of the node allow it to receive power over the communication cabling.

2. A power supply subsystem according to claim 1, wherein said voltage measuring means is operative to measure the voltage at the output of said current limiting circuitry.

3. A power supply subsystem according to claim 1, wherein said voltage measuring means is operative to measure the voltage supplied to the communication cabling.

4. A power supply subsystem according to claim 1, wherein said power management and control unit is further operable, prior to said coupling said current limited output to the communication cabling, to measure, utilizing said voltage measuring means, a pre-existing voltage present across a line associated with the communication cabling.

5. A power supply subsystem according to claim 4, wherein in the event that said measured pre-existing voltage exceeds a predetermined threshold, said power management and control unit is further operable to classify the line as externally voltage fed.

6. A power supply subsystem according to claim 5, wherein said power management and control unit is operative to couple said current limited output to the communication cabling only in the event that the line is not classified as externally voltage fed.

7. A power supply subsystem according to claim 1, wherein said power management and control unit further determines the status of the local area network node for which power is to be provided as a consequence of said measured voltage, said status comprising one of a short circuit condition, a no load condition, a network interface card load condition and a power over LAN load condition.

8. A power supply subsystem according to claim 7, wherein said power management and control unit is further operable to report said status to a network workstation.

9. A method for supplying power to a local area network node over communication cabling, the method comprising:

injecting current-limited current into communication cabling connected to the local area network node;

measuring a voltage developed in accordance with said injected current limited current across said communication cabling at three pre-determined intervals; and

determining, as a consequence of said measured voltage at said three pre-determined intervals whether characteristics of the local area network node allow it to receive power over the communication cabling.

10. A method according to claim 9, wherein said measuring is accomplished at the output of a current-limited supplying circuitry, said current-limited supplying circuitry supplying said injected current-limited current.

11. A method according to claim 9, wherein said measuring is accomplished across a line associated with the communication cabling.

12. A method according to claim 9, further comprising prior to said injecting, measuring a pre-existing voltage across a line associated with the communication cabling.

13. A method according to claim 12, further comprising:

in the event said measured pre-existing voltage exceeds a predetermined threshold,

classifying the line associated with the communication cabling as externally voltage fed.

14. A method according to claim 13, wherein said injecting is performed only in the event that said measured pre-existing voltage does not exceed said predetermined threshold.

15. A method according to claim 9, further comprising determining a status of the local area network node for which power is to be provided over the communication cabling, said status comprising one of a short circuit condition, a no load condition, a network interface card load condition and a power over LAN load condition.

16. A method according to claim 15, wherein said determining a status of the local area network node is a consequence of said measured voltage.

17. A method according to claim 15, further comprising reporting said determined status to a network workstation.

18. A local area network providing power over communication cabling comprising:

a LAN switch;

a plurality of local area network nodes;

communication cabling enabling data communication between said LAN switch and said plurality of local area network nodes; and

a power supply subsystem, said power supply subsystem comprising;

a power management and control unit;

current limiting circuitry responsive to said power management and control unit to supply a current limited output;

voltage measurement means; and

at least one of a combiner and a power supply interface operative to couple said current limited output to said communication cabling,

said power management and control unit being operative to;

measure, utilizing said voltage measuring means at three intervals, a voltage developed in accordance with said coupled programmable current limited output; and

determine, as a consequence of said measured voltage whether characteristics of at least one of said plurality of local area network nodes allow it to receive power over said communication cabling.

19. A local area network according to claim 18, wherein said voltage measuring means is operative to measure the voltage at the output of said programmable current limiting circuitry.

20. A local area network according to claim 18, wherein said voltage measuring means is operative to measure the voltage supplied to said communication cabling.

21. A local area network according to claim 18, wherein said power management and control unit is further operable, prior to said coupling of said current limited output to said communication cabling, to measure utilizing said voltage measuring means, a pre-existing voltage present across a line associated with said communication cabling.

22. A local area network according to claim 21, wherein in the event that said measured pre-existing voltage exceeds a predetermined threshold, said power management and control unit is further operable to classify said line as externally voltage fed.

23. A local area network according to claim 22, wherein said power management and control unit is operative to couple said current limited output to said communication cabling only in the event that said line is not classified as externally voltage fed.

24. A local area network according to claim 18, wherein said power management and control unit further determines the status of said at least one of said plurality of local area network nodes for which power is to be provided, said status comprising one of a short circuit condition, a no load condition, a network interface card load condition and a power over LAN load condition.

25. A local area network according to claim 24, wherein said determined status if a consequence of said measured voltage.

26. A local area network according to claim 24, further comprising a network workstation, said power management and control unit reporting said status to said network workstation.

27. A local area network according to claim 18, wherein said power supply subsystem and said LAN switch are located in a hub.

28. A local area network according to claim 18, wherein said power supply subsystem is located between said LAN switch and said at least one of said plurality of local area network nodes.

29. A local area network according to claim 18, wherein said power supply subsystem is located between said LAN switch and said plurality of network nodes, said communication cabling connecting said LAN switch and said plurality of network nodes via said power supply subsystem.

30. A power supply subsystem for providing electrical power to a local area network node over communication cabling, the power supply subsystem comprising:

a power management and control unit;

current limiting circuitry responsive to said power management and control unit to supply a current limited output;

voltage measurement means;

at least one of a combiner and a power supply interface operative to couple said current limiting output to the communication cabling;

said power management and control unit being operative to;

measure, utilizing said voltage measuring means at three pre-determined intervals, a voltage developed in accordance with said coupled current limited output, said voltage being measured across a line associated with the communication cabling;

determine, as a consequence of said measured voltage at said three pre-determined intervals whether characteristics of the node allow it to receive power over the communication cabling; and

in the event that said characteristics of the node allow it to receive power over the communication cabling, provide said programmable current limited output via said at least one of a combiner and a power supply interface over the communication cabling to the node.