System and method for signaling and detecting request for power over ethernet

• US 6,535,983 B1
• Filed: 11/08/1999
• Issued: 03/18/2003
• Est. Priority Date: 11/08/1999
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Stapleton, Nicholas Mark, Dryer, Paul Francis, McCormack, Michael S.
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): SURYAWANSHI, SURESH
• Application Number:
  US09/435,722
• Time in Patent Office: 1,226 Days
• Field of Search: 713/310, 713/15, 370/908, 370/410
• US Class Current: 713/310
• 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
• CPC Class Codes: H04L 12/12 Arrangements for remote connection or disconnection of substations or of equipment thereof

Abstract

According to the invention, an Ethernet system and method of using an Ethernet system is provided including a network side device (a hub/switch/concentrator), and a plurality of end devices (either a standard end device powered locally or a system powered device), connected to the hub/switch. The system powered devices have circuitry for indicating the system power need to the hub, which has a power source for selectively supplying system power over the Ethernet. A stimulus device associated with the network device sends a stimulus signal over the network connection lines during a detection phase. The need for power is signaled by an indication device associated with the system powered end devices, providing an indication signal in response to the stimulus signal. A detector associated with the network side detects the indication signal thus triggering the power source to supply system power to each of the end devices that is a system powered device and not to each of the end devices that is a standard device.

Claims

1. A network system comprising:

a network device having ports;

wiring defining network connection lines for carrying data signals;

a plurality of end devices, each end device being connected to ports of said network device via respective network connection lines, said end devices including at least one of a system powered end device, requiring power via said network connection lines and a locally powered end device, not requiring power via said network connection lines.

2. The system according to claim 1, wherein said system powered end device includes a load and said indication device isolates said load during said detection phase.

3. The system according to claim 1, wherein said stimulus device is associated with a power source for powering said system powered end device during an operation phase.

4. The system according to claim 3, wherein said stimulus device and said detection device are isolated from said power source during said detection phase.

5. The system according to claim 1, wherein said stimulus device and said detection device include common circuitry.

6. A system to power twisted pair wires carrying Ethernet data signals, the system comprising:

a hub/switch;

Ethernet twisted pair wiring;

a variable power source with current sense for providing a power voltage during a power phase and for oscillating between a first low voltage and a second low voltage during a pre-power phase, said variable power source being associated with said hub/switch for supplying said first low voltage and said second low voltage, for supplying a power voltage over said twisted pair wires carrying Ethernet data signals and for detecting current draw in the twisted pair wires carrying Ethernet data;

a device connectable to the hub/switch via the twisted pair wires carrying Ethernet data signals, said device having circuitry for allowing current flow at said second low voltage and for substantially not allowing current flow at said first low voltage whereby said current sense of said power source senses an expected current draw behavior to indicate the device is to be powered by said power source.

7. The system according to claim 6, wherein said circuitry for allowing current flow at said second low voltage and for substantially not allowing current flow at said first low voltage includes a Zener diode selected based on said first low voltage and a second low voltage.

8. The system according to claim 6, further comprising a standard end device connectable with hub/switch via the twisted pair wires carrying Ethernet data signals, said standard end device including a passive resistor termination to an associated twisted pair wires carrying Ethernet data signals.

9. An Ethernet system comprising:

a hub/switch;

Ethernet twisted pair wiring for carrying data signals;

a plurality of end devices connected by said Ethernet twisted pair wiring to said hub/switch, each end device being one of;

a standard end device connectable with said hub/switch via the twisted pair wires carrying Ethernet data signals, said standard end device including a passive resistor termination to an associated twisted pair wires carrying Ethernet data signals and

a system powered device connectable to the hub/switch via the twisted pair wires carrying Ethernet data signals, said system powered device providing a nonlinear current draw upon a voltage oscillating between a first low voltage and a second low voltage being applied to said system powered end device for indicating the system power need to said hub; and

a power source for selectively supplying system power over said Ethernet twisted pair wiring, said power source being a variable power source with a power off state in which said variable power source oscillates between said first low voltage and said second low voltage said power source being associated with said hub and detecting said nonlinear current draw upon said voltage oscillating between said first low voltage and said second low voltage being applied to said system powered end device to indicate the system power need and supplying system power to each of said end devices that is a system powered device and for not supplying system power to each of said end devices that is a standard device.

10. The system according to claim 9, wherein the system power is above 5V and the Ethernet twisted pair wiring for carrying data signals carries the system power as a component with a series superimposed communication pulse component for Ethernet twisted pair wiring connected to a system powered device.

11. The system according to claim 10, wherein the Ethernet twisted pair wiring for carrying data signals carries a signal including a 60 Hz ISO 48V potential component and a series superimposed communication pulse (e.g. +/−

2V) component.

12. The system according to claim 9, wherein said system powered device provides a nonlinear current draw with circuitry for allowing current flow at said second low voltage and for substantially not allowing current flow at said first low voltage;

and said power source detects said indication of the system power need with current sense circuitry which senses a current draw which is non linear, based on said system powered device circuitry allowing current flow at said second low voltage and substantially not allowing current flow at said first low voltage to indicate the device is to be powered by said power source.

13. The system according to claim 12, wherein said circuitry for allowing current flow at said second low voltage and for substantially not allowing current flow at said first low voltage includes a Zener diode selected based on said first low voltage and a second low voltage.

14. A process for selectively providing system power to end devices using Ethemet twisted pair wiring, the process comprising the steps of:

providing a hub/switch including a power source having a detecting state oscillating between a first low voltage and a second low voltage;

providing Ethernet twisted pair wiring for carrying data signals;

connecting a plurality of end devices to the hub/switch with the Ethernet twisted pair wiring, each of the devices being one of

a standard end device connectable with said hub/switch via the twisted pair wires carrying Ethernet data signals, the standard end device including a passive resistor termination to an associated twisted pair wires carrying Ethernet data signals and

a system powered device connectable to the hub/switch via the twisted pair wires carrying Ethernet data signals, said system powered device providing a nonlinear current draw upon a voltage oscillating between the first low voltage and the second low voltage being applied to said system powered end device for indicating the system power need to said hub;

detecting said nonlinear current draw at the hub/switch upon said voltage oscillating between said first low voltage and said second low voltage being applied to said system powered end device to indicate the system power need; and

supplying system power to each of the end devices that is a system powered device and for not supplying system power to each of said end devices that is a standard device based on the detected indication.

15. The process according to claim 14, wherein the system power is above 5V and the Ethernet twisted pair wiring for carrying data signals carries the system power as a component with a series superimposed communication pulse component for Ethernet twisted pair wiring connected to a system powered device.

16. The process according to claim 15, wherein the Ethernet twisted pair wiring for carrying data signals carries a signal including a 60 Hz ISO 48V potential component and a series superimposed communication pulse (e.g. +/−

2 V) component.

17. The process according to claim 14, wherein said power source is a variable power source with the detecting state in which it oscillates between providing the first low voltage and providing the second low voltage, said variable power source supplying the first low voltage and the second low voltage and wherein said system powered device includes circuitry for allowing current flow at said second low voltage and for substantially not allowing current flow at said first low voltage to provide the indication.

18. The process according to claim 17, wherein said power source detects said indication of the system power need with current sense circuitry which senses a current draw which is non linear, based on said system powered device circuitry allowing current flow at said second low voltage and substantially not allowing current flow at said first low voltage to indicate the device is to be powered by said power source.

19. The process according to claim 16, wherein said power source enters said power off state either by default or the state is entered upon detecting a connection condition at an end device side.

20. The process according to claim 14, wherein the second voltage is greater than the first low voltage.