Automatic power over ethernet pulse width signaling correction
First Claim
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1. A circuit, comprising:
- a first comparator for measuring a load current in a powered device (PD) and for comparing the load current to a reference and generating an output signal;
a timing logic circuit responsive to the output signal for generating an enable signal;
a pulse generator responsive to the enable signal to generate a current pulse having an amplitude determined in response to a difference between a total load current on the PD and a minimum current required by a standard when coupled to a Power Sourcing Equipment (PSE) to automatically signal the PSE to maintain power supplied to the PD; and
a correction circuit for measuring the amplitude of the generated current pulse to determine when the measured amplitude exceeds an active level and for generating a corrected reference signal for maintaining the measured pulse at a current level above the active level for a predetermined period of time for signaling the PSE to maintain power to the PD.
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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. The pulse widths of the load pulses are measured and the widths are automatically adjusted, that power to the PD should be maintained.
26 Citations
18 Claims
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1. A circuit, comprising:
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a first comparator for measuring a load current in a powered device (PD) and for comparing the load current to a reference and generating an output signal; a timing logic circuit responsive to the output signal for generating an enable signal; a pulse generator responsive to the enable signal to generate a current pulse having an amplitude determined in response to a difference between a total load current on the PD and a minimum current required by a standard when coupled to a Power Sourcing Equipment (PSE) to automatically signal the PSE to maintain power supplied to the PD; and a correction circuit for measuring the amplitude of the generated current pulse to determine when the measured amplitude exceeds an active level and for generating a corrected reference signal for maintaining the measured pulse at a current level above the active level for a predetermined period of time for signaling the PSE to maintain power to the PD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An interface, comprising;
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a pulse generator for generating a current pulse having an amplitude determined in response to a difference between a total load current on a powered device (PD) and the minimum current required by a standard from the PD coupled to a Power Sourcing Equipment (PSE) to automatically signal the PSE to provide power to the PD; a pulse corrector for determining when the generated current pulse reaches an active level for indicating that power to the PD from the PSE is to be maintained and for generating a corrected reference signal for maintaining the generated current pulse at a current above the active level for a predetermined period of time for indicating that power to the PD is to be maintained; and an error amplifier for controlling the amplitude of the generated current pulse responsive to the corrected reference signal and responsive to a PD load current measurement. - View Dependent Claims (14, 15)
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16. A method, comprising:
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generating a current pulse having an amplitude determined in response to a difference between a total load current on a powered device (PD) and the minimum current required by a standard from a PD coupled to a Power Sourcing Equipment (PSE) to automatically signal the PSE to provide power to the PD; determining when the generated current pulse reaches an active level for indicating that power to the PD from the PSE is to be maintained; responsive to a PD load current measurement, maintaining the generated current pulse at a current level above the active level for a predetermined period of time for indicating that power to the PD is to be maintained; and controlling the amplitude of the generated current pulse responsive to a correction reference signal generated in response to the determination of when the generated current pulse reaches the active level. - View Dependent Claims (17, 18)
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Specification