Employing sense resistor as safety fuse in Limited Power Source Applications

• US 20040236967A1
• Filed: 05/19/2003
• Published: 11/25/2004
• Est. Priority Date: 05/19/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: PowerDsine Limited (Microchip Technology Incorporated)
• Inventors: Giat, Yaniv, Korcharz, Dror, Peker, Arkadiy
• Granted Patent: US 7,225,345 B2
• Time in Patent Office: Days
• US Class Current: 713/300
• 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: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision

Abstract

A communication network utilizing Power Over Ethernet technology including Power Sourcing Equipment (PSE) that includes a multi-purpose device that operates as a current sensing resistor under normal electrical operating conditions and operates as a protection device, e.g., a fuse, under fault conditions, such as, an internal switch failure and an overload occurring simultaneously.

Claims

1. A communication network comprising:

at least one communication device operable to transmit or receive communications over the network; and

a power sourcing device connected to said communication device via cabling and operable to provide electrical power to said communication device, said power sourcing device being a limited power source, wherein said power sourcing device comprises a general purpose resistor pre-selected to provide both a current sensing function by which an amount of electrical current drawn by said communication device is determined and a fault protection function by which the output of said communication device is disconnected during a predetermined fault condition.

2. A communication network as claimed in claim 1, wherein said power sourcing device performs data communication with said communication device.

3. A communication network as claimed in claim 1, wherein the fault condition comprises a failure in a power switch and an overload condition in either or both of said communication device and the cabling connecting said communication device and said power sourcing device.

4. A communication network as claimed in claim 1, wherein the fault condition comprises an open circuit.

5. A communication network as claimed in claim 1, wherein said power sourcing device is protected in accordance with a published standard.

9. A communication network as claimed in claim 1, wherein said power sourcing device is an end-span PSE device in accordance with power over Ethernet (POE) technology.

10. A communication network as claimed in claim 1, wherein said power sourcing device is a mid-span PSE device in accordance with power over Ethernet (POE) technology.

15. A communication network as claimed in claim 5, wherein said general purpose resistor limits the electrical current drawn by said communication device from said power sourcing device in accordance with the published standard.

16. A communication network as claimed in claim 15, wherein an amount of power drawn by said communication device is limited to 100 VA.

6-8. -8. (Cancelled)

11. A communication network comprising:

at least one communication device operable to transmit or receive communications over the network; and

a limited power source operable to provide electrical power to said communication device over communication cabling connecting said limited power source to said at least one communication device, wherein said limited power source comprises a general purpose resistor for providing a protection function by which said communication device is electrically protected from a fault condition.

12-14. -14. (Canceled)

17. A power sourcing device for providing electrical power to one or more communication devices, the power sourcing device comprising:

a power switch operable to selectively provide power to the communication devices over a standard communication interface;

a general purpose resistor pre-selected to provide a current sensing function by which the amount of electrical current drawn by said communication device is determined and a protection function by which said communication device is electrically disconnected from the electrical power during a fault condition;

whereby said power sourcing device is a limited power source as specified in a published safety standard.

18. A power sourcing device as claimed in claim 17, further comprising:

a control section connected to said power switch and operable to selectively turn-on or turn-off said power switch, said control section being further operable to determine an amount of electrical current flowing through said general purpose resistor.

19. A power sourcing device as claimed in claim 17, wherein the standard communication interface is an Ethernet interface.

20. A power sourcing device as claimed in claim 17, wherein the communication devices are networked in a Local Area Network configuration adapted to accommodate Power Over Ethernet technology.

21. A power sourcing device as claimed in claim 17, wherein the general purpose resistor is a surface mount resistor.

25. A power sourcing device as claimed in claim 17, wherein said power sourcing device is an end-span PSE device in accordance with power over Ethernet (POE) technology.

26. A power sourcing device as claimed in claim 17, wherein said power sourcing device is a mid-span PSE device in accordance with power over Ethernet (POE) technology.

22-24. -24. (Cancelled)