HYSTERETIC BUCK CONVERTER HAVING DYNAMIC THRESHOLDS
First Claim
1. A buck switching voltage regulator circuit, comprising:
- a comparison circuit for providing a first indication when a voltage of an output of the buck switching voltage regulator circuit does not exceed a first threshold magnitude and providing a second indication when the voltage of the output of the buck switching regulator circuit exceeds a second threshold magnitude, wherein the second threshold magnitude is greater than the first threshold magnitude;
an inductive storage element;
a switching circuit for coupling the inductive storage element between an input of the buck switching voltage regulator circuit and the output of the buck switching voltage regulator circuit in response to the first indication, and coupling the inductive storage element between the output of the buck switching voltage regulator circuit and a return path of the output of the buck switching voltage regulator circuit in response to the second indication; and
a control circuit for generating the first threshold magnitude and the second threshold magnitude, such that the first threshold magnitude increases with increases in an output current provided by the output of the buck switching voltage regulator circuit to a load and decreases with decreases in the output current, and wherein the control circuit calculates an indication of the output current and sets the first threshold magnitude in conformity therewith.
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Accused Products
Abstract
A hysteretic buck converter provides improved regulation control, in particular for buck converter standby operation. A comparison circuit compares the output voltage of the buck converter to a waveform that is generated from an indication of the output current of the converter, so that the turn-on time of the converter is advanced as the output current demand increases. The resulting action anticipates a reduction in output voltage due to the increased current, preventing an excursion of the output voltage below the ripple voltage minimum. The turn-off time of the converter is controlled by an upper threshold that limits the ripple voltage maximum. The output current indication may be a measurement of output current, or may be a dynamic value calculated from the input voltage and the output voltage waveform.
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Citations
24 Claims
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1. A buck switching voltage regulator circuit, comprising:
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a comparison circuit for providing a first indication when a voltage of an output of the buck switching voltage regulator circuit does not exceed a first threshold magnitude and providing a second indication when the voltage of the output of the buck switching regulator circuit exceeds a second threshold magnitude, wherein the second threshold magnitude is greater than the first threshold magnitude; an inductive storage element; a switching circuit for coupling the inductive storage element between an input of the buck switching voltage regulator circuit and the output of the buck switching voltage regulator circuit in response to the first indication, and coupling the inductive storage element between the output of the buck switching voltage regulator circuit and a return path of the output of the buck switching voltage regulator circuit in response to the second indication; and a control circuit for generating the first threshold magnitude and the second threshold magnitude, such that the first threshold magnitude increases with increases in an output current provided by the output of the buck switching voltage regulator circuit to a load and decreases with decreases in the output current, and wherein the control circuit calculates an indication of the output current and sets the first threshold magnitude in conformity therewith. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A buck switching voltage regulator circuit, comprising:
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a comparison circuit for providing a first indication when a voltage of an output of the buck switching voltage regulator circuit does not exceed a first threshold magnitude and providing a second indication when the voltage of the output of the buck switching regulator circuit exceeds a second threshold magnitude, wherein the second threshold magnitude is greater than the first threshold magnitude; an inductive storage element; a switching circuit for coupling the inductive storage element between an input of the buck switching voltage regulator circuit and the output of the buck switching voltage regulator circuit in response to the first indication, and coupling the inductive storage element between the output of the buck switching voltage regulator circuit and a return path of the output of the buck switching voltage regulator circuit in response to the second indication; and a control circuit for generating the first threshold magnitude as a waveform at a rate greater than or equal to a switching period of the switching circuit, wherein the first indication is generated repetitively to control a start of the switching period, and wherein the waveform is generated such that the first indication occurs earlier in time within the switching period as an output current provided by the output of the buck switching voltage regulator circuit to a load increases and occurs later in time within the switching period as the output current decreases.
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13. A method for regulating the output voltage of a buck switching voltage regulator circuit, comprising:
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first comparing a voltage of an output of the buck switching voltage regulator circuit to a first threshold magnitude; second comparing the voltage of the output of the buck switching voltage regulator circuit to a second threshold magnitude, wherein the second threshold magnitude is greater than the first threshold magnitude; coupling an inductive storage element between an input of the buck switching voltage regulator circuit and the output of the buck switching voltage regulator circuit when the first comparing indicates that the voltage of the output of the buck switching voltage regulator circuit does not exceed the first threshold magnitude; coupling the inductive storage element between the output of the buck switching voltage regulator circuit and a return path of the output of the switching voltage regulator circuit when the second comparing indicates that the voltage of the output of the buck switching voltage regulator circuit exceeds the second threshold magnitude; and controlling values of the first threshold magnitude and the second threshold magnitude, such that the first threshold magnitude increases with increases in output current provided by the output of the buck switching voltage regulator circuit to a load and decreases with decreases in the output current, by calculating an indication of an output current provided by the output of the buck switching voltage regulator circuit to a load and setting the first threshold magnitude in conformity therewith. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for regulating the output voltage of a buck switching voltage regulator circuit, comprising:
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first comparing a voltage of an output of the buck switching voltage regulator circuit to a first threshold magnitude; second comparing the voltage of the output of the buck switching voltage regulator circuit to a second threshold magnitude, wherein the second threshold magnitude is greater than the first threshold magnitude; coupling an inductive storage element between an input of the buck switching voltage regulator circuit and the output of the buck switching voltage regulator circuit when the first comparing indicates that the voltage of the output of the buck switching voltage regulator circuit does not exceed the first threshold magnitude; coupling the inductive storage element and between the output of the buck switching voltage regulator circuit and a return path of the output of the switching voltage regulator circuit when the second comparing indicates that the voltage of the output of the buck switching voltage regulator circuit exceeds the second threshold magnitude; and generating the first threshold magnitude as a waveform at a rate greater than or equal to a switching period of the switching circuit, wherein the first indication is generated repetitively to control a start of the switching period, and wherein the waveform is generated such that the first indication occurs earlier in time within the switching period as an output current provided by the output of the buck switching voltage regulator circuit to a load increases and occurs later in time within the switching period as the output current decreases.
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Specification