Powered device for power over ethernet system with increased cable length

• US 20080315682A1
• Filed: 12/03/2007
• Published: 12/25/2008
• Est. Priority Date: 06/22/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Hussain, Asif
• Granted Patent: US 8,026,627 B2
• Time in Patent Office: Days
• US Class Current: 307/2
• CPC Class Codes: H04L 12/10 Current supply arrangements

Abstract

A Powered Device (PD) in a Power Over Ethernet system that supports increased cable lengths of more than 100 m is provided herein. The proposed PD design requires no modifications at the PSE side. Embodiments include example modifications of IEEE 802.3af PD system rules, including example modifications of PD classification and port voltage ranges to enable increased cable length PoE.

Claims

1. A Powered Device (PD) for use in a Power over Ethernet (PoE) system, comprising:

a PD chip having a port voltage range having a minimum voltage that is lower than an IEEE compliant minimum PD port voltage;

wherein said minimum voltage is determined according to a maximum voltage drop across an Ethernet cable that connects said PD and a power source equipment (PSE); and

wherein said Ethernet cable is at least approximately 100 meters long.

2. The PD of claim 1, wherein said Ethernet cable is one of a CAT-3, CAT-5, CAT-5e, CAT-6, CAT-6a, or CAT-7 cable.

3. The PD of claim 1, wherein said PSE provides a voltage to said PD, said voltage is in compliance with a PoE standard.

4. The PD of claim 1, wherein said PSE provides a voltage to said PD, said voltage is in compliance with the IEEE 802.3af standard.

5. The PD of claim 1, wherein said PSE provides a voltage to said PD, said voltage is in compliance with the IEEE 802.3at standard.

6. The PD of claim 1, wherein said PD chip supports a minimum of approximately 13 volts during a classification phase and a minimum of approximately 18.5 volts after a startup phase, thereby enabling said Ethernet cable to be up to approximately 350 meters long when said PSE is an IEEE 802.3af compliant PSE and said PD is a class 0-3 PD.

7. The PD of claim 1, wherein said PD chip supports a minimum of approximately 12 volts during a classification phase and a minimum of approximately 8 volts after a startup phase, thereby enabling said Ethernet cable to be up to approximately 500 meters long when said PSE is an IEEE 802.3af compliant PSE and said PD is a class 0-3 PD.

8. The PD of claim 1, wherein said PD chip supports a minimum of approximately 11.9 volts during a classification phase and a minimum of approximately 18.5 volts after a startup phase, thereby enabling said Ethernet cable to be up to approximately 350 meters long when said PSE is an IEEE 802.3af compliant PSE and said PD is a class 0-4 PD.

9. The PD of claim 1, wherein said PD chip supports a minimum of approximately 10.4 volts during a classification phase and a minimum of approximately 8 volts after a startup phase, thereby enabling said Ethernet cable to be up to approximately 500 meters long when said PSE is an IEEE 802.3af compliant PSE and said PD is a class 0-4 PD.

10. The PD of claim 1, wherein said PD chip:

dynamically determines said port voltage range according to the length of said Ethernet cable;

dynamically detects a power class of said PD; and

dynamically calculates V_on and V_off power levels of said PD according to the length of said Ethernet cable.

11. 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 PD supports a port voltage range having a minimum voltage that is lower than an IEEE compliant minimum PD port voltage, said minimum voltage determined according to a maximum voltage drop across said Ethernet cable; and

wherein said PSE is in compliance with at least one of the IEEE 802.3af standard, the IEEE 802.3at standard, and a legacy PoE standard.

12. The PoE system of claim 11, wherein said Ethernet cable is one of a CAT 3, CAT5, CAT 5e, CAT 6, CAT 6a, or CAT 7 cable.

13. The PoE system of claim 11, wherein said PSE provides at least approximately 6.4 Watts at said PD when a PSE port voltage is equal to 44 volts, and at least approximately 11 Watts when said PSE port voltage is equal to 57 volts.

14. The PoE system of claim 11, wherein said Ethernet cable is approximately 350 meters long.

15. The PoE system of claim 11, wherein said Ethernet cable is approximately 500 meters long.

16. A method for enabling an increased reach Power over Ethernet (PoE) system, comprising:

determining a resistance of a cable connecting a Power Source Equipment (PSE) and a Powered Device (PD) of a PoE system;

detecting a power class of said PD; and

determining a port voltage range and a classification voltage range for said PD according to said power class of said PD and said cable resistance;

configuring said PD according to said determined port voltage range and classification voltage range; and

receiving a voltage from said PSE at said PD.

17. The method of claim 16, wherein said voltage received at said PD has a minimum of approximately 13 volts during a classification phase and a minimum of approximately 18.5 volts after a startup phase, thereby enabling said cable to be up to approximately 350 meters long when said PD is a class 0-3 PD.

18. The method of claim 16, wherein said voltage received at said PD has a minimum of approximately 12 volts during a classification phase and a minimum of approximately 8 volts after a startup phase, thereby enabling said cable to be up to approximately 500 meters long when said PD is a class 0-3 PD.

19. The method of claim 16, wherein said voltage received at said PD has a minimum of approximately 11.9 volts during a classification phase and a minimum of approximately 18.5 volts after a startup phase, thereby enabling said cable to be up to approximately 350 meters long when said PD is a class 0-4 PD.

20. The method of claim 16, wherein said voltage received at said PD has a minimum of approximately 10.4 volts during a classification phase and a minimum of approximately 8 volts after a startup phase, thereby enabling said cable to be up to approximately 500 meters long when said PD is a class 0-4 PD.