Lossless overcurrent sensing circuit for voltage regulator
First Claim
1. An overcurrent sensing circuit for voltage regulators comprising:
- at least a first voltage regulator circuit including;
(a) an input;
(b) an output;
(c) a field effect transistor having a source, a drain, and a gate, and being disposed between said input and said output so that current can flow from said input through the drain and the source to said output; and
,(d) voltage feedback means connected between said output and a first input of an amplifier circuit, said amplifier circuit generating as an output, a control voltage that is fed to the gate of the field effect transistor, said control voltage being responsive to the circuit output voltage; and
,means to sense when the magnitude of said control voltage exceeds a set point at which said field effect transistor is driven into saturation thereby, said point being indicative of an overcurrent condition between said input and said output.
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Accused Products
Abstract
An overcurrent sensing circuit for use with a voltage regulator, such as a linear post regulator for a power supply, utilizes a field effect transistor (FET) both as the pass element for the voltage regulator, and as a current sense resistor. The output voltage from the FET is fed back to an input of a differential amplifier, which generates a control voltage for the gate of the FET, so that the output voltage will remain constant. If an overcurrent condition occurs through the FET, the control voltage will exceed a set point, thus driving the FET into saturation, and sensing circuitry will generate an overcurrent output that can be utilized to shut off the regulator. A single sensing circuit can be used for multiple regulators if desired.
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Citations
5 Claims
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1. An overcurrent sensing circuit for voltage regulators comprising:
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at least a first voltage regulator circuit including; (a) an input; (b) an output; (c) a field effect transistor having a source, a drain, and a gate, and being disposed between said input and said output so that current can flow from said input through the drain and the source to said output; and
,(d) voltage feedback means connected between said output and a first input of an amplifier circuit, said amplifier circuit generating as an output, a control voltage that is fed to the gate of the field effect transistor, said control voltage being responsive to the circuit output voltage; and
,means to sense when the magnitude of said control voltage exceeds a set point at which said field effect transistor is driven into saturation thereby, said point being indicative of an overcurrent condition between said input and said output. - View Dependent Claims (2, 3, 4, 5)
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Specification