Circuit and method for preventing reverse current flow into a voltage regulator from an output thereof
First Claim
1. A circuit for interrupting current flow into a voltage regulator from an output of the voltage regulator, the circuit comprising:
- a comparator including an output, an input coupled to a voltage source, and an input coupled to the output of the voltage regulator; and
a number of transistors coupled to the output of the comparator and controlled thereby, the number of transistors including a first transistor configured to interrupt a first current path extending between the output of the voltage regulator and the voltage source through an output leg of the voltage regulator when a voltage of the voltage source (Vpwr) drops below a voltage at the output of the voltage regulator (Vout).
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0 Petitions
Accused Products
Abstract
A circuit and method are provided for interrupting current flow into a voltage regulator from an output thereof when a voltage source (Vpwr) drops below an output voltage (Vout). In one embodiment, the circuit comprises: (i) a comparator supplied by Vout including an output and inputs coupled to Vpwr and Vout; and (ii) transistors coupled to and controlled by the comparator, including a first transistor configured to interrupt a first current path extending between Vout and Vpwr through an output-leg of the regulator when Vpwr drops below Vout. Preferably, the regulator includes a reference-leg and a feedback-circuit coupling Vout thereto, and the first transistor also interrupts a second current path between Vout and Vpwr through the feedback-circuit and reference leg. More preferably, the reference-leg comprises resistors through which it is coupled to ground, and the transistors include a second transistor to interrupt a third current path between Vout and ground.
80 Citations
20 Claims
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1. A circuit for interrupting current flow into a voltage regulator from an output of the voltage regulator, the circuit comprising:
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a comparator including an output, an input coupled to a voltage source, and an input coupled to the output of the voltage regulator; and a number of transistors coupled to the output of the comparator and controlled thereby, the number of transistors including a first transistor configured to interrupt a first current path extending between the output of the voltage regulator and the voltage source through an output leg of the voltage regulator when a voltage of the voltage source (Vpwr) drops below a voltage at the output of the voltage regulator (Vout). - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for interrupting current flow into a voltage regulator from an output thereof, the method comprising steps of:
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comparing a voltage (Vpwr) of a voltage source coupled to the voltage regulator to a voltage (Vout) at the output of the voltage regulator; and controlling a number of transistors to substantially prevent current flowing from the output of the voltage regulator into the voltage regulator when Vpwr drops below Vout. - View Dependent Claims (9, 10, 11, 12, 13, 20)
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14. A voltage regulator comprising:
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a comparator including an output, a non-inverting input coupled to a voltage source and an inverting input coupled to an output of the voltage regulator; and a number of transistors coupled to the output of the comparator and controlled thereby to substantially prevent current from flowing from the output of the voltage regulator into the voltage regulator when a voltage of a voltage source (Vpwr) of the voltage regulator drops below a voltage at the output of the voltage regulator (Vout). - View Dependent Claims (15, 16, 17, 18, 19)
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Specification