Power FET gate charge recovery
First Claim
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1. An apparatus comprising:
- a first transistor configured to provide an output voltage when the first transistor is turned on;
a first switching transistor configured to turn the first transistor on;
a second switching transistor configured to turn the first transistor off, wherein the first and second switching transistors are configured to be separately switched;
a regulated voltage supply coupled to the first switching transistor;
a first charge-storage device coupled to the regulated voltage supply;
a first path between the first transistor and the first charge storage device;
a first switching device along the first path, the first switching device configured to conduct at least a first portion of a charge from the first transistor to the first charge-storage device when the first transistor transitions from on to off;
a diode along the first path, the diode configured to prevent a flow of charge along the first path from the first charge-storage device to the first transistor; and
a second path between the first charge-storage device and at least one of the first switching transistor and the second switching transistor.
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Abstract
A circuit for recovering charge at the gate of an output transistor arranged to drive the output of a switching circuit such as a switching regulator or controller. A substantial portion of the charge for each switching cycle is recovered under a wide range of load conditions for the switching circuit, e.g., no load, partial load, or full load. Also, charge recovery operates effectively with a switching circuit that is arranged to switch in a synchronous or asynchronous manner. Additionally, if the output voltage of a switching circuit is 12 or more volts, the amount of charge that can be saved can be relatively substantial.
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Citations
20 Claims
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1. An apparatus comprising:
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a first transistor configured to provide an output voltage when the first transistor is turned on; a first switching transistor configured to turn the first transistor on; a second switching transistor configured to turn the first transistor off, wherein the first and second switching transistors are configured to be separately switched; a regulated voltage supply coupled to the first switching transistor; a first charge-storage device coupled to the regulated voltage supply; a first path between the first transistor and the first charge storage device; a first switching device along the first path, the first switching device configured to conduct at least a first portion of a charge from the first transistor to the first charge-storage device when the first transistor transitions from on to off; a diode along the first path, the diode configured to prevent a flow of charge along the first path from the first charge-storage device to the first transistor; and a second path between the first charge-storage device and at least one of the first switching transistor and the second switching transistor. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus comprising:
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a first transistor configured to provide an output voltage when the first transistor is turned on; a regulated voltage supply coupled to the first transistor; a first charge-storage device coupled to the regulated voltage supply; a first path between the first transistor and the first charge storage device; a first switching device configured to conduct at least a first portion of a charge from the first transistor to the first charge-storage device when the first transistor transitions from on to off; a diode along the first path, the diode configured to prevent a flow of charge along the first path from the first charge-storage device to the first transistor; and a second path between the first charge-storage device and at least one of a first switching transistor and a second switching transistor. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A method comprising:
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transitioning a first transistor from on to off, the first transistor configured to provide an output voltage when the first transistor is turned on; during the transition of the first transistor from on to off, conducting, along a first path, at least a first portion of a charge from the first transistor to a first charge-storage device for storage; and preventing, with a diode, a flow of charge along the first path from the first charge-storage device to the first transistor; and allowing a flow of charge along a second path from the first-charge-storage device to an input of at least one of a first switching transistor and a second switching transistor. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification