Power over ethernet powered device having automatic power signature
First Claim
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1. A powered device (PD) for use in a power over Ethernet (PoE) system, the PD device comprising:
- first and second voltage supply terminals associated with the PoE system;
a return terminal associated with a load;
a detection circuit configured to generate a maintain power signature (MPS) enable signal upon detecting a load current, between the return terminal and the second voltage supply terminal, less than a first MPS reference threshold; and
a MPS generation circuit configured to generate a MPS pulse upon receiving the MPS enable signal, the MPS generation circuit configured to regulate an amplitude of the MPS pulse based on a second MPS reference threshold.
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Abstract
In a Power over Ethernet (PoE) system, a Powered Device (PD) having circuitry to measure the load current from a Power Sourcing Equipment (PSE) in the PD. Circuitry compares the measured load current with a first threshold. Circuitry automatically generates load pulses for signaling the PSE, that power to the PD should be maintained.
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Citations
20 Claims
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1. A powered device (PD) for use in a power over Ethernet (PoE) system, the PD device comprising:
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first and second voltage supply terminals associated with the PoE system; a return terminal associated with a load; a detection circuit configured to generate a maintain power signature (MPS) enable signal upon detecting a load current, between the return terminal and the second voltage supply terminal, less than a first MPS reference threshold; and a MPS generation circuit configured to generate a MPS pulse upon receiving the MPS enable signal, the MPS generation circuit configured to regulate an amplitude of the MPS pulse based on a second MPS reference threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An integrated circuit (IC) for use in a powered device (PD) of a power over Ethernet (PoE) system, the IC comprising:
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first and second voltage supply terminals associated with the PoE system; a return terminal associated with a load; a detection circuit including; an amplifier stage having a sense node configured to develop a sense voltage representative of a load current between the return terminal and the second voltage supply terminal; and a comparator having a non-inverting input coupled to the sense node, an inverting input coupled to receive a first maintain power signature (MPS) reference threshold, and an output configured to deliver an MPS enable signal; and an MPS generation circuit configured to generate a MPS pulse between the first and second voltage supply terminals and upon receiving the MPS enable signal, the MPS generation circuit configured to regulate an amplitude of the MPS pulse based on a second MPS reference threshold. - View Dependent Claims (16, 17)
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18. An integrated circuit (IC) for use in a power delivery (PD) device of a power over Ethernet (PoE) system, the IC comprising:
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first and second voltage supply terminals associated with the PoE system; a return terminal associated with a load; a first stage includes a first transistor coupled between the return terminal and a sense node, and a first resistor coupled between the sense node and the second voltage supply terminal; a second stage includes a second transistor coupled between the return terminal and an MPS node, and a second resistor coupled between the MPS node and the sense node; a comparator configured to assert a maintain power signature (MPS) enable signal when a sense voltage at the sense node is less than a first MPS reference threshold, and configured to reset the MPS enable signal when the sense voltage is greater than the first MPS reference threshold; a timing logic configured to enable the first stage and disable the second stage when the MPS enable signal is reset, and configured to disable the first stage and enable the second stage when the MPS enable signal is asserted; and a MPS generation circuit configured to generate a MPS pulse, at the MPS node, upon receiving the MPS enable signal, the MPS generation circuit configured to regulate an amplitude of the MPS pulse based on a second MPS reference threshold. - View Dependent Claims (19, 20)
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Specification