Pre-detection of powered devices

• US 20040260794A1
• Filed: 06/07/2004
• Published: 12/23/2004
• Est. Priority Date: 06/10/2003
• 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: Darshan, Yair, Ferentz, Alon, Korcharz, Dror
• Granted Patent: US 7,849,343 B2
• Time in Patent Office: Days
• US Class Current: 709/220
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: H04L 12/10 Current supply arrangements

Abstract

A method and apparatus for preventing harmful transients resulting from a probing routine for a valid powered device detection signature in a network, the method comprising: operating power sourcing equipment to provide via its output port a pre-detection output voltage; obtaining an indication of the pre-detection output voltage; comparing the indication of the pre-detection output voltage with a pre-determined value; and in the event that the indication of the pre-detection output voltage is less than the pre-determined value; initiating a probing routine for a valid powered device detection signature. The higher voltage of the probing routine is thus not present at the output port in the absence of pre-detection of a potentially valid powered device detection signature.

Claims

1. A method for preventing harmful transients resulting from a probing routine for a valid powered device detection signature in a network, the method comprising:

operating power sourcing equipment to provide via its output port a pre-detection output voltage;

obtaining an indication of said pre-detection output voltage;

comparing said indication of said pre-detection output voltage with a pre-determined value; and

in the event that said indication of said pre-detection output voltage is less than said pre-determined value;

initiating a probing routine for a valid powered device detection signature.

2. A method according to claim 1, wherein said operating power sourcing equipment comprises connecting one of a voltage source and a current source to said output port.

3. A method according to claim 2, wherein said connecting one of a voltage source and a current source to said output port is accomplished through a known impedance.

4. A method according to claim 3, wherein said known impedance comprises a source impedance.

5. A method according to claim 1, wherein said initiating a probing routine for a valid powered device detection signature comprises:

operating said power sourcing equipment to provide via its output port a first detection output voltage;

obtaining an indication of said first detection output voltage;

operating said power sourcing equipment to provide via its output port a second detection output voltage different from said first detection output voltage;

obtaining an indication of said second detection output voltage; and

identifying a valid powered device detection signature as a consequence of said obtained indications of said first and second detection output voltages.

6. A method according to claim 5, further comprising after performing said obtaining an indication of said first detection output voltage, comparing said obtained indication of said first detection output voltage with a pre-determined range.

7. A method according to claim 6, wherein said operating said power sourcing equipment to provide via its output port a second detection output voltage is performed only in the event said obtained indication of said first detection output voltage is within said pre-determined range.

8. A method according to claim 5, wherein said pre-detection output voltage is substantially equivalent to said first detection output voltage.

9. A method according to claim 1, wherein said pre-detection output voltage comprises two output voltages, the method further comprising determining a difference between said obtained indications of said pre-detection output voltages, said comparing said indication of said pre-detection output voltage being accomplished utilizing said determined difference.

10. A method according to claim 1, wherein said power sourcing equipment is operated such that said pre-detection output voltage in the absence of a connected valid powered device is less than or equal to 5 volts.

11. A method according to claim 1, wherein said power sourcing equipment is operated such that said pre-detection output voltage in the absence of a connected valid powered device is less than or equal to 3 volts.

12. A method according to claim 1, wherein said valid powered device detection signature is in accordance with the IEEE 802.3 af standard.

13. A method according to claim 1, wherein said pre-determined value is representative of a load having an impedance less than 100 Kohm.

14. A method according to claim 1, wherein said pre-determined value is representative of a load having an impedance less than 75 Kohm.

15. Power sourcing equipment for detecting and powering a valid powered device in an Ethernet network, the power sourcing equipment comprising:

one of a voltage source and a current source;

an output port; and

control circuitry;

said control circuitry being operable to;

provide from said one of a voltage source and a current source via said output port a pre-detection output voltage;

obtain an indication of said pre-detection output voltage;

compare said obtained indication of said pre-detection output voltage with a pre-determined value; and

in the event that said obtained indication of said pre-detection output voltage is less than said pre-determined value;

initiate a probing routine for a valid powered device detection signature.

16. Power sourcing equipment according to claim 15, further comprising a known impedance, said pre-detection output voltage being provided to said output port through said known impedance from said one of a voltage source or a current source.

17. Power sourcing equipment according to claim 16, wherein said known impedance comprises a source impedance.

18. Power sourcing equipment according to claim 15, wherein said control circuitry is operable such that said pre-detection voltage at said output port in the absence of a connected valid powered device is below a threshold for causing harmful transients.

19. Power sourcing equipment according to claim 15, wherein said initiate a probing routine for a valid powered device detection signature comprises:

provide from said one of a voltage source and a current source via said output port a first detection output voltage;

obtain an indication of said first detection output voltage;

provide from said one of a voltage source and a current source via its output port a second detection output voltage;

obtain an indication of said second detection output voltage at said output port; and

identify a valid powered device detection signature as a consequence of said obtained indications of said first and second detection output voltages.

20. Power sourcing equipment according to claim 19, wherein said control circuitry is further operable after said obtaining of said indication of said first detection output voltage, to compare said obtained indication of said first detection output voltage with a pre-determined range.

21. Power sourcing equipment according to claim 20, wherein said control circuit is operable to provide via said output port said second detection output voltage only in the event said obtained indication of said first detection output voltage is within said predetermined range.

22. Power sourcing equipment according to claim 19, wherein said pre-detection output voltage is substantially equivalent to said first detection output voltage.

23. Power sourcing equipment according to claim 15, wherein said pre-detection output voltage comprises two pre-detection output voltages, said control circuitry being operable to determine a difference between said obtained indications of said two pre-detection voltages, and wherein said comparing said indication of said pre-detection output voltage is accomplished utilizing said determined difference.

24. Power sourcing equipment according to claim 15, wherein said control circuitry is operable such that said pre-detection output voltage in the absence of a connected valid powered device is less than or equal to 5 volts.

25. Power sourcing equipment according to claim 15, wherein said control circuitry is operable such that said pre-detection output voltage in the absence of a connected valid powered device is less than or equal to 3 volts.

26. Power sourcing equipment according to claim 15, wherein said valid powered device detection signature is in accordance with the IEEE 802.3 af standard.

27. Power sourcing equipment according to claim 15, wherein said pre-determined value is representative of a valid powered device signature.

28. Power sourcing equipment according to claim 15, wherein said pre-determined value is representative of a load impedance less than 100 Kohm.

29. Power sourcing equipment according to claim 15, wherein said pre-determined value is representative of a load impedance less than 75 Kohm.

30. A method for preventing harmful transients while enabling detection of a valid powered device detection signature in a network, the method comprising:

operating power sourcing equipment to provide via its output port a first output voltage;

obtaining an indication of said first output voltage;

comparing said obtained indication of said first output voltage with a pre-determined value; and

in the event that said obtained indication of said first output voltage is less than said pre-determined value;

operating said power sourcing equipment to provide via its output port a second output voltage thereby probing for a valid powered device detection signature.

31. A method for detecting a valid powered device detection signature in a network, the method comprising:

operating power sourcing equipment to provide via its output port a first voltage;

measuring said first voltage at said output port;

comparing said measured first voltage with a pre-determined value; and

in the event that said measured first voltage is less than said pre-determined value;

operating said power sourcing equipment to provide via its output port at least two additional voltages;

measuring said at least two additional voltages at said output port; and

determining a valid powered device detection signature utilizing said measured first voltage and said measured two additional voltages.

32. A method according to claim 31, wherein said first voltage comprises a plurality of voltages, the method further comprising calculating a difference between two of said plurality of voltages, said comparing said first voltage with a pre-determined value being accomplished by comparing said difference with a pre-determined value.

33. A method for preventing harmful transients while enabling detection of a valid powered device detection signature in a network, the method comprising:

operating power sourcing equipment to provide via its output port two first output voltages;

obtaining an indication of each of said two first output voltages;

determining a difference between said obtained indication of said two first output voltages;

comparing said determined difference with a pre-determined value; and

in the event that said determined difference is less than said pre-determined value;

operating said power sourcing equipment to provide via its output port a second output voltage thereby probing for a valid powered device detection signature.

34. A method according to claim 33, wherein said probing for a valid powered device detection signature comprises said two first output voltages and said second output voltage.

35. A method according to claim 33, wherein said pre-determined value is indicative of a potentially valid powered device detection signature.

36. A system for detecting and powering a valid powered device in an Ethernet network comprising:

a powered device; and

power sourcing equipment coupled by communication cabling to said powered device, said power sourcing equipment being operable to;

provide via its output port a pre-detection voltage;

obtain an indication of said pre-detection voltage at said output port;

compare said obtained indication of said pre-detection voltage at said output port with a pre-determined value; and

in the event that said obtained indication is less than said pre-determined value;

initiate a probing routine for a valid powered device detection signature.