US 2015/0091391 A1Published application

Detection and classification scheme for power over ethernet system

AssigneeLinear Technology Corporation

InventorsDavid Dwelley, Jeffrey Heath, Kirk Su, Ryan Huff

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Abstract

In a method performed by a PoE system, a PSE provides data and operating voltage over Ethernet wires to a PD. Before the full PoE voltage is supplied, the PSE generates a low current signal received by the PD. A circuit in the PD, connected across its input terminals, has a characteristic analog response to the PSE signal corresponding to the PD's PoE requirements, such as whether the PD is a Type 1 or Type 2 PD. The circuit may be a certain value capacitor, zener diode, resistor, or other circuit. The PSE may generate a fixed current, fixed voltage, or time varying signal. Upon the PSE sensing the magnitude of the analog signal response at a particular time, the PSE associates the response with the PoE requirements of the PD. The PSE then applies the full PoE voltage in accordance with the PD's PoE requirements.

Claims22

Dependent claims

A Power Over Ethernet (PoE) system comprising:

Power Sourcing Equipment (PSE) providing data and voltage over Ethernet wires, the PSE having a voltage source for generating a PoE voltage for transmission on the Ethernet wires;
and
a Powered Device (PD) connected to the PSE by at least the Ethernet wires to receive the data and voltage, the PD comprising a first circuit electrically coupled to input terminals of the PD, wherein the first circuit has characteristics, wherein the first circuit responds in a predetermined manner to a first signal generated by the PSE to create a second signal, and wherein the first circuit is selected to convey particular PoE requirements of the PD;
the PSE further comprising:
a first signal generator providing the first signal on the Ethernet wires to the input terminals of the PD at a particular time, wherein the first signal is applied to the first circuit in the PD;
a first detector detecting a varying analog amplitude of the resulting second signal, generated by the first circuit in the PD, in response to the first signal;
and
a processing circuit configured for detecting a magnitude of the varying amplitude of the second signal after an elapsed time and, in response to the detected magnitude after the elapsed time, associating the second signal with the particular PoE requirements of the PD, and controlling the PSE to supply power to the PD via the Ethernet wires consistent with the PoE requirements of the PD conveyed by the second signal.

5 more elements

A Power Over Ethernet (PoE) system comprising:

Power Sourcing Equipment (PSE) providing data and voltage over Ethernet wires, the PSE having a voltage source for generating a PoE voltage for transmission on the Ethernet wires;
and
a Powered Device (PD) connected to the PSE by at least the Ethernet wires to receive the data and voltage, the PD comprising a first circuit electrically coupled to input terminals of the PD, wherein the first circuit has characteristics, wherein the first circuit responds in a predetermined manner to a first signal generated by the PSE to create a second signal, and wherein the first circuit is selected to convey particular PoE requirements of the PD;
the PSE further comprising:
a first signal generator providing the first signal on the Ethernet wires to the input terminals of the PD at a particular time, wherein the first signal is applied to the first circuit in the PD;
a first detector detecting a voltage-limited second signal, generated by the first circuit in the PD, in response to the first signal;
and
a processing circuit configured for detecting a limited voltage of the second signal and, in response to a detected magnitude of the second signal, associating the second signal with the particular PoE requirements of the PD, and controlling the PSE to supply power to the PD via the Ethernet wires consistent with the PoE requirements of the PD conveyed by the second signal.

5 more elements

Dependencies are inferred from the claim text.