Circuits and methods for detecting the presence of a powered device in a powered network
First Claim
1. A circuit for detecting the presence of a powered device in a powered network connection, the circuit comprising:
- an oscillator for providing a time-varying voltage signal; and
an analog amplifier circuit for receiving the time-varying voltage signal from the oscillator as an input, applying the time-varying voltage signal to the powered network connection, and sensing the current flowing through a coupling capacitor required to drive a load connected to the analog amplifier circuit.
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Abstract
Circuits and methods for detecting the presence of a powered device in a powered network connection and removing power from the powered network connection when no powered device is present are disclosed. The circuits and methods involve applying a time-varying voltage signal into an analog amplifier circuit that converts the voltage into a current indicative of the impedance of the connection. The analog amplifier circuit may be implemented with a dual-output trans-conductance amplifier that provides a digital voltage to indicate the removal of the powered device from the powered network connection.
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Citations
39 Claims
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1. A circuit for detecting the presence of a powered device in a powered network connection, the circuit comprising:
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an oscillator for providing a time-varying voltage signal; and
an analog amplifier circuit for receiving the time-varying voltage signal from the oscillator as an input, applying the time-varying voltage signal to the powered network connection, and sensing the current flowing through a coupling capacitor required to drive a load connected to the analog amplifier circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A power sourcing equipment for providing power to a powered network connection, the power sourcing equipment comprising:
an AC disconnect circuit for detecting the presence of a powered device in a powered network connection, the AC disconnect circuit comprising;
an oscillator for providing a time-varying voltage signal; and
an analog amplifier circuit for receiving the time-varying voltage signal from the oscillator as an input, applying the time-varying voltage signal to the powered network connection, and sensing the current flowing through a coupling capacitor required to drive a load connected to the analog amplifier circuit. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for detecting the presence of a powered device in a powered network connection and removing power from the powered network connection when the powered device is disconnected from the powered network connection, the method comprising:
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detecting a valid powered device signature in the powered network connection;
supplying power to the powered network connection if a valid powered device signature is detected;
applying a time-varying voltage signal into the powered network connection;
converting the time-varying voltage signal into a current with an analog amplifier circuit; and
measuring the impedance of the powered network connection by sensing the current flowing through a coupling capacitor connected to the analog amplifier circuit. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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Specification