Methods and apparatus providing advanced classification for power over Ethernet

• US 20080244284A1
• Filed: 03/27/2007
• Published: 10/02/2008
• 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: Schindler, Frederick Roland, Karam, Roger A., Jones, Chad M.
• Granted Patent: US 7,921,307 B2
• Time in Patent Office: Days
• 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 the powered device, each cycle having a detection phase and a classification phase, a classification voltage applied to the conductors during each cycle, and measuring a current in the conductors while the classification voltage is applied; and

determining 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.

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:

determining whether the powered device is capable of storing a memory of a voltage received by the powered device.

3. The method of claim 2 wherein determining the powered device is capable of storing a memory of a voltage received by the powered device comprises:

determining the memory is retained by the powered device when a voltage of approximately eight to ten volts is received by the powered device.

4. The method of claim 2 wherein determining the powered device is capable of storing a memory of a voltage received by the powered device comprises:

determining the memory of the powered device is cleared when a voltage of approximately three to five volts is received by the powered device.

5. 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.

6. The method of claim 5 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 about ten volts to detect a valid powered device.

7. 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.

8. The method of claim 7 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.

9. The method of claim 5 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.

10. 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 at least one cycle having a signature phase.

11. 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 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 cycle; and

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

circuitry for providing an amount of inline power responsive to a plurality of measured currents.

12. The power sourcing equipment of claim 11 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.

13. The power sourcing equipment of claim 12 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.

14. The circuitry of claim 13 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

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, 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, the currents collectively corresponding to predetermined inline power classes.

16. The powered device of claim 15 wherein the circuitry responsive to a plurality of cycles comprises:

circuitry capable of storing a memory of a voltage received by the powered device.

17. The powered device of claim 16 wherein the circuitry capable of storing a memory of a voltage received by the powered device comprises:

circuitry capable of retaining the memory when a voltage of approximately eight to ten volts is received by the powered device from the power source equipment.

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 computerized device with a means for classifying a powered device, the means including;

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

means for determining 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.

19. The computer system of claim 18 wherein said means for conducting a plurality of cycles on the powered device, each cycle having a detection phase and a classification phase further comprises:

determining whether the powered device is capable of storing a memory of a voltage received by the powered device.

20. 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 the powered device, each cycle having a detection phase and a classification phase, a classification voltage applied to the conductors during each cycle, and measuring a current in the conductors while the classification voltage is applied; and

instructions for determining 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.