Method and apparatus for sensing a current in a circuit
First Claim
1. A current sense circuit, comprising:
- a current sense resistor coupled to an input of the current sense circuit, the current sense resistor to receive a current to be sensed from the input of the current sense circuit to convert the current to be sensed to a current sense voltage;
a first PN junction diode coupled to the current sense resistor; and
a light emitting diode (LED) coupled to the first PN junction diode to provide a current sense threshold substantially equal to a difference between a forward voltage drop of the first PN junction diode and a fraction of a forward voltage drop of the LED, the first PN junction diode coupled to be biased from the forward voltage drop of the LED, the LED coupled to the current sense resistor to generate an output when the current sense voltage from the current sense resistor reaches the current sense threshold.
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Abstract
Techniques are disclosed to sense a current in a circuit. For instance, current sense circuit according to the teachings of the present invention includes a current sense resistor coupled to an input of the current sense circuit. The current sense resistor is coupled to receive a current to be sensed from the input of the current sense circuit. The current to be sensed is converted to a current sense voltage. A first PN junction diode is coupled to the current sense resistor. A light emitting diode (LED) is coupled to the first PN junction diode to provide a current sense threshold substantially proportional to a difference between a forward voltage drop of the LED and a forward voltage drop of the first PN junction diode. The first PN junction diode is coupled to be biased from the forward voltage drop of the LED. The LED is coupled to the current sense resistor to generate an output when the current sense voltage from the current sense resistor reaches the current sense threshold.
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Citations
20 Claims
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1. A current sense circuit, comprising:
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a current sense resistor coupled to an input of the current sense circuit, the current sense resistor to receive a current to be sensed from the input of the current sense circuit to convert the current to be sensed to a current sense voltage; a first PN junction diode coupled to the current sense resistor; and a light emitting diode (LED) coupled to the first PN junction diode to provide a current sense threshold substantially equal to a difference between a forward voltage drop of the first PN junction diode and a fraction of a forward voltage drop of the LED, the first PN junction diode coupled to be biased from the forward voltage drop of the LED, the LED coupled to the current sense resistor to generate an output when the current sense voltage from the current sense resistor reaches the current sense threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A current sense circuit, comprising:
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a current sense resistor coupled to a direct current (DC) output of a power supply, wherein the current sense circuit is to be powered entirely from the DC output, wherein the current sense resistor is to convert a current at the DC output into a current sense voltage; and a PN junction diode coupled to the current sense resistor, wherein a current sense threshold is less than a forward voltage of the PN junction diode by a fraction of a forward voltage drop of a light emitting diode (LED) coupled to the PN junction diode, wherein the current sense circuit is to generate an output when the current sense voltage reaches the current sense threshold to sense or regulate the current at the DC output. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification