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

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.

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.

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.