Methods and apparatus providing advanced classification for power over Ethernet

• US 7,921,307 B2
• Filed: 03/27/2007
• Issued: 04/05/2011
• Est. Priority Date: 03/27/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Jones, Chad M., Schindler, Frederick Roland, Karam, Roger A.
• Primary Examiner(s): TRAN, VINCENT HUY
• Application Number:
  US11/728,743
• Publication Number:
  US 20080244284A1
• Time in Patent Office: 1,470 Days
• Field of Search: 713/300, 370/400, 370/395.53
• US Class Current: 713/300
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence

Abstract

A system conducts a plurality of cycles on the powered device. Each cycle has a detection phase and a classification phase. A classification voltage is applied to the conductors during each cycle. The system measures a current in the conductors while the classification voltage is applied. The system determines a final class responsive to a plurality of measured currents. The final class utilized to determine an amount of inline power to deliver to the powered device.

Claims

1. A method for classifying a powered device coupled to power sourcing equipment to receive inline power from the power sourcing equipment in a wired data telecommunications network having at least two pairs of conductors coupling the powered device and the power sourcing equipment, the method comprising:

conducting a plurality of cycles on at least the two pairs of conductors of the powered device, each cycle having a detection phase and a classification phase, a classification voltage applied to the conductors during each classification phase, and measuring a current in the conductors while the classification voltage is applied; and

determining a final class responsive to the measured currents of each of the plurality of cycles, the final class utilized to determine an amount of inline power to deliver to the powered device.

2. The method of claim 1 wherein conducting a plurality of cycles on the powered device, each cycle having a detection phase and a classification phase comprises:

conducting each cycle within the plurality of cycles such that each cycle begins with a detection phase followed by a classification phase, each of the classification phase applying a respective classification voltage to the conductors, and measuring the current in the conductors while the classification voltage is applied, the plurality of cycles containing at least two cycles; and

determining a respective class at the completion of each of the at least two cycles, the respective class computed by the current measured in the conductors.

3. The method of claim 2 wherein conducting each cycle within the plurality of cycles such that each cycle begins with a detection phase followed by a classification phase comprises:

conducting the detection phase by applying at least one detection voltage of less than the classification voltage to detect a valid powered device.

4. The method of claim 2 wherein conducting each cycle within the plurality of cycles such that each cycle begins with a detection phase followed by a classification phase comprises:

conducting the detection phase by applying at least one detection current to detect a valid powered device.

5. The method of claim 1 wherein determining a final class responsive to the measured currents comprises:

detecting the plurality of cycles comprises three cycles, each of the three cycles producing a class, each class associated with the measured current received at the powered device during each of the three cycles, each of the three classes received in an order in which each of the three cycles is completed; and

based on the order in which the three cycles were received, determining a final class associated with the amount of inline power to deliver to the powered device.

6. The method of claim 5 comprising:

detecting the plurality of cycles comprises a fourth cycle producing a fourth class that is used to determine the amount of inline power to deliver to the powered device by adding an incremental value to the amount of inline power that is determined as a result of the three classes produced by the three cycles.

7. The method of claim 1 wherein conducting a plurality of cycles on the powered device, comprises:

conducting at least one cycle having a signature phase by applying a signature voltage different from the classification voltage, where the signature voltage identifies a type of the power sourcing equipment to the powered device.

8. The method of claim 1 further comprising:

conducting a mutual identification cycle by applying a voltage to the conductors that is different than the classification voltage and causes the powered device to detect a type of the power sourcing equipment.

9. Power sourcing equipment adapted to classify a coupled powered device so that the powered device can receive inline power from the power sourcing equipment in a wired data telecommunications network having at least two pairs of conductors coupling the powered device and the power sourcing equipment, the power sourcing equipment comprising:

circuitry for conducting a plurality of cycles on at least the two pairs of conductors for at least one classification procedure having a detection phase and a classification phase, the at least one classification procedure comprising a classification voltage applied to the conductors during each classification phase; and

measuring the current in the conductors while the classification voltage is applied; and

circuitry for providing an amount of inline power responsive to the measured currents of each of the plurality of cycles.

10. The power sourcing equipment of claim 9 wherein the circuitry for conducting a plurality of cycles for at least one classification procedure comprises:

circuitry for conducting each cycle within the plurality of cycles such that each cycle begins with a detection phase followed by a classification phase, each of the classification phase applying a classification voltage to the conductors during each cycle, and circuitry for measuring the current in the conductors while the classification voltage is applied, the plurality of cycles containing at least two cycles; and

circuitry for determining a respective class at the completion of each of the at least two cycles, the class computed by the current measured in the conductors.

11. The power sourcing equipment of claim 10 wherein the circuitry for determining a respective class at the completion of each of the at least two cycles comprises:

circuitry for detecting that the plurality of cycles comprises three cycles, each of the three cycles producing a class, each class associated with the measured current received at the powered device during each of the three cycles, each of the three classes received in the order in which each of the three cycles, within the plurality of cycles, was completed; and

circuitry for determining a final class associated with the amount of inline power to deliver to the powered device, based on the order of the three cycles.

12. The circuitry of claim 11 comprising:

circuitry for detecting the plurality of cycles comprises a fourth cycle producing a fourth class that is used to determine the amount of inline power to deliver to the powered device by adding an incremental value to the amount of inline power that is determined as a result of the three classes produced by the three cycles.

13. The power sourcing equipment of claim 9 further comprising:

circuitry for conducting a mutual identification cycle by applying a voltage to the conductors that is different than the classification voltage and causes the powered device to detect a type of the power sourcing equipment.

14. The power sourcing equipment of claim 9 further comprising:

circuitry for conducting at least one cycle having a signature phase by applying a signature voltage different from the classification voltage, where the signature voltage identifies a type of the power sourcing equipment to the powered device.

15. A powered device adapted to operate in conjunction with a coupled power sourcing equipment so that the powered device can receive inline power from the power sourcing equipment in a wired data telecommunications network having at least two pairs of conductors coupling the powered device and the power sourcing equipment, the powered device comprising:

circuitry responsive to a plurality of cycles on at least the two pairs of conductors, each cycle having a detection phase and a classification phase, the cycles produced by the power sourcing equipment, the circuitry presenting a series of currents over the conductors to the power sourcing equipment responsive to a classification voltage applied during the classification phase of each of the plurality of cycles, the currents collectively corresponding to predetermined inline power classes.

16. The powered device of claim 15 further comprising:

circuitry for identifying a mutual identification cycle by detecting a voltage to the conductors that is different than the classification voltage, to thereby allow the powered device to detect a type of the power sourcing equipment.

17. The powered device of claim 15 further comprising:

circuitry for identifying at least one cycle having a signature phase comprising a signature voltage different from the classification voltage, where the signature voltage identifies a type of the power sourcing equipment to the powered device; and

circuitry for responding to the signature phase.

18. A computer system comprising:

a memory;

a processor;

a communications interface;

an interconnection mechanism coupling the memory, the processor and the communications interface;

wherein the memory is encoded with a powered device classifying application that when executed on the processor configures the processor to perform an operation for classifying a powered device, the operation including;

conducting a plurality of cycles on at least two pairs of the conductors coupled to the powered device, each cycle having a detection phase and a classification phase, a classification voltage applied to the conductors during each classification phase, and measuring a current in the conductors while the classification voltage is applied; and

determining a final class responsive to the measured currents for each of the plurality of cycles, the final class utilized to determine an amount of inline power to deliver to the powered device.

19. The computer system of claim 18 wherein the operation further comprises:

conducting a mutual identification cycle by applying a voltage to the conductors that is different than the classification voltage and causes the powered device to detect a type of the power sourcing equipment.

20. The computer system of claim 18 wherein the operation further comprises:

conducting at least one cycle having a signature phase by applying a signature voltage different from the classification voltage, where the signature voltage identifies a type of the power sourcing equipment to the powered device.

21. A computer readable medium encoded with computer programming logic that when executed on a process in a computerized device provides powered device classification, the medium comprising:

instructions for conducting a plurality of cycles on at least two pairs of conductors coupled to the powered device, each cycle having a detection phase and a classification phase, a classification voltage applied to the conductors during each classification phase, and measuring a current in the conductors while the classification voltage is applied; and

instructions for determining a final class responsive to the measured currents for each of the plurality of cycles, the final class utilized to determine an amount of inline power to deliver to the powered device.