Boost and up-down switching regulator with synchronous freewheeling MOSFET
First Claim
1. A DC/DC voltage converter comprising:
- an inductor and a low-side switch connected in a series conduction path between first and second supply voltages, the inductor being coupled to the first supply voltage and the low-side switch being coupled to the second supply voltage, a Vx node being located in the series conduction path between the inductor and the low-side switch;
an energy transfer switch connected between the Vx node and an output terminal of the converter; and
a freewheeling switch connected in parallel with the inductor, the freewheeling switch comprising a freewheeling MOSFET and a body bias generator, the body bias generator being coupled to each of first and second conduction terminals and a body of the freewheeling MOSFET, the body bias generator being adapted to short the body to one of the first and second conduction terminals of the freewheeling MOSFET responsive to a relationship between voltages present at the first and second conduction terminals, respectively, of the freewheeling MOSFET so as to prevent any P-N junction in the freewheeling MOSFET from becoming forward-biased.
1 Assignment
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Accused Products
Abstract
A freewheeling MOSFET is connected in parallel with the inductor in a switched DC/DC converter. When the freewheeling MOSFET is turned on during the switching operation of the converter, while the low-side and energy transfer MOSFETs are turned off, the inductor current circulates or “freewheels” through the freewheeling MOSFET. The frequency of the converter is thereby made independent of the lengths of the magnetizing and energy transfer stages, allowing far greater flexibility in operating and converter and overcoming numerous problems associated with conventional DC/DC converters. For example, the converter may operate in either step-up or step-down mode and may even transition for one mode to the other as the values of the input voltage and desired output voltage vary.
48 Citations
43 Claims
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1. A DC/DC voltage converter comprising:
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an inductor and a low-side switch connected in a series conduction path between first and second supply voltages, the inductor being coupled to the first supply voltage and the low-side switch being coupled to the second supply voltage, a Vx node being located in the series conduction path between the inductor and the low-side switch; an energy transfer switch connected between the Vx node and an output terminal of the converter; and a freewheeling switch connected in parallel with the inductor, the freewheeling switch comprising a freewheeling MOSFET and a body bias generator, the body bias generator being coupled to each of first and second conduction terminals and a body of the freewheeling MOSFET, the body bias generator being adapted to short the body to one of the first and second conduction terminals of the freewheeling MOSFET responsive to a relationship between voltages present at the first and second conduction terminals, respectively, of the freewheeling MOSFET so as to prevent any P-N junction in the freewheeling MOSFET from becoming forward-biased. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A DC/DC voltage converter comprising:
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an inductor and a low-side switch connected in a series conduction path between first and second supply voltages, the inductor being coupled to the first supply voltage and the low-side switch being coupled to the second supply voltage, a Vx node being located in the series conduction path between the inductor and the low-side switch; an energy transfer switch connected between the Vx node and an output terminal of the converter; and a freewheeling switch connected in parallel with the inductor, the freewheeling switch comprising a freewheeling MOSFET and a body bias generator with integrated adaptive clamping, the body bias generator comprising a first body bias MOSFET coupled between a body and a first conduction terminal of the freewheeling MOSFET and a second body bias MOSFET coupled between the body and a second conduction terminal of the freewheeling MOSFET, a gate of the first body bias MOSFET being coupled to the second conduction terminal of the freewheeling MOSFET, a gate of the second body bias MOSFET being coupled to a gate buffer and the gate buffer being coupled to a comparator, respective input terminals of the comparator being connected such that the comparator compares a value of the first supply voltage and a value of an output voltage at the output terminal. - View Dependent Claims (15, 16, 17, 18)
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19. A DC/DC voltage converter comprising:
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an inductor and a low-side switch connected in a series conduction path between first and second supply voltages, the inductor being coupled to the first supply voltage and the low-side switch being coupled to the second supply voltage, a Vx node being located in the series conduction path between the inductor and the low-side switch; an energy transfer switch connected between the Vx node and an output terminal of the converter; a freewheeling switch connected in parallel with the inductor; and an adaptive clamping circuit comprising a clamping diode connected to the Vx node, the adaptive clamping circuit being adapted to clamp the Vx node to either the first supply voltage or an output voltage at the output terminal depending on a relationship between the first supply voltage and the output voltage. - View Dependent Claims (20, 21)
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22. A method of converting a DC input voltage to a DC output voltage comprising:
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applying the DC input voltage to a first terminal of an inductor while coupling a second terminal of the inductor to a circuit ground so as to magnetize the inductor; disconnecting the second terminal of the inductor from the circuit ground;
coupling the second terminal of the inductor to a capacitor and an output terminal so as to provide the DC output voltage at the output terminal; disconnecting the second terminal of the inductor from the capacitor and the output terminal; connecting the first and second terminals of the inductor together while the second terminal of the inductor is disconnected from the capacitor and the output terminal; with the first and second terminals of the inductor connected together, detecting the value of a decreasing current through the inductor; and disconnecting the first and second terminals of the inductor when the detected value of the current through the inductor falls below a predetermined level. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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31. A DC/DC voltage converter comprising:
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an inductor and a low-side switch connected in a series conduction path between first and second supply voltages, the inductor being coupled to the first supply voltage and the low-side switch being coupled to the second supply voltage, a Vx node being located in the series conduction path between the inductor and the low-side switch; an energy transfer switch connected between the Vx node and an output terminal of the converter, the energy transfer switch comprising a synchronous rectifier MOSFET and a body bias generator, the body bias generator being coupled to each of first and second conduction terminals and a body of the synchronous rectifier MOSFET, the body bias generator being adapted to short the body to one of the first and second conduction terminals of the synchronous rectifier MOSFET responsive to a relationship between voltages present at the first and second conduction terminals, respectively, of the synchronous rectifier MOSFET so as to prevent any P-N junction in the synchronous rectifier MOSFET from becoming forward-biased; and
an adaptive clamping circuit comprising a clamping diode connected to the Vx node, the adaptive clamping circuit being adapted to clamp the Vx node to either the first supply voltage or an output voltage at the output terminal depending on a relationship between the first supply voltage and the output voltage. - View Dependent Claims (32, 33)
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34. A method of converting a DC input voltage to a DC output voltage comprising:
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(a) during a time interval tON, applying the DC input voltage to a first terminal of an inductor while coupling a second terminal of the inductor to a circuit ground so as to magnetize the inductor; (b) at the termination of the time interval tON, disconnecting the second terminal of the inductor from the circuit ground; (c) during a time interval tXFER, coupling the second terminal of the inductor to a capacitor and an output terminal so as to provide the DC output voltage at the output terminal; (d) at the termination of the time interval tXFER, disconnecting the second terminal of the inductor from the capacitor and the output terminal;
(e) during a time interval tFW, connecting the first and second terminals of the inductor together while the second terminal of the inductor is disconnected from the capacitor and the output terminal; and (f) at the termination of the time interval tFW, disconnecting the first and second terminals of the inductor; repeating (a)-(f) in the same sequence multiple times, wherein at each repetition tON +tXFER +tFW equals a time period T; and while repeating (a)-(f) in the same sequence multiple times, varying the length of at least one of the time intervals toN and tXFER while adjusting the time interval tFW as required to maintain the time period T at a first fixed value and to maintain the DC output voltage at a second fixed value; the method comprising performing (b) immediately after (a), (e) immediately after (b), (f) immediately after (e), (c) immediately after (f) and (d) immediately after (c).
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35. A method of converting a DC input voltage to a DC output voltage comprising:
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(a) during a time interval tON, applying the DC input voltage to a first terminal of an inductor while coupling a second terminal of the inductor to a circuit ground so as to magnetize the inductor; (b) at the termination of the time interval tON, disconnecting the second terminal of the inductor from the circuit ground; (c) during a time interval tXFER, coupling the second terminal of the inductor to a capacitor and an output terminal so as to provide the DC output voltage at the output terminal; (d) at the termination of the time interval tXFER, disconnecting the second terminal of the inductor from the capacitor and the output terminal; (e) during a time interval tFW, connecting the first and second terminals of the inductor together while the second terminal of the inductor is disconnected from the capacitor and the output terminal; and
(f) at the termination of the time interval tFW, disconnecting the first and second terminals of the inductor; and repeating (a)-(f) in the same sequence multiple times, while maintaining toN at a first fixed value and adjusting the length of at least one of the time intervals txFER and tFW as required to maintain the DC output voltage at a second fixed value; the method comprising performing (b) immediately after (a), (e) immediately after (b), (f) immediately after (e), (c) immediately after (f) and (d) immediately after (c).
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36. A method of converting a DC input voltage to a DC output voltage comprising:
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(a) during a time interval tON, applying the DC input voltage to a first terminal of an inductor while coupling a second terminal of the inductor to a circuit ground so as to magnetize the inductor; (b) at the termination of the time interval tON, disconnecting the second terminal of the inductor from the circuit ground; (c) during a time interval tXFER, coupling the second terminal of the inductor to a capacitor and an output terminal so as to provide the DC output voltage at the output terminal; (d) at the termination of the time interval tXFER, disconnecting the second terminal of the inductor from the capacitor and the output terminal; (e) during a time interval tFW, connecting the first and second terminals of the inductor together while the second terminal of the inductor is disconnected from the capacitor and the output terminal; and (f) at the termination of the time interval tFW, disconnecting the first and second terminals of the inductor; and repeating (a)-(f) in the same sequence multiple times, while maintaining tFW at a fixed value. - View Dependent Claims (37, 38)
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39. A method of converting a DC input voltage to a DC output voltage comprising:
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(a) during a time interval tON, applying the DC input voltage to a first terminal of an inductor while coupling a second terminal of the inductor to a circuit ground so as to magnetize the inductor; (b) at the termination of the time interval tON, disconnecting the second terminal of the inductor from the circuit ground; (c) during a time interval tXFER, coupling the second terminal of the inductor to a capacitor and an output terminal so as to provide the DC output voltage at the output terminal; (d) at the termination of the time interval tXFER, disconnecting the second terminal of the inductor from the capacitor and the output terminal; repeating (a)-(d) multiple times while detecting the DC output voltage; and when the detected DC output voltage is greater than a target level, performing the following (e) and (f) at least once; (e) during a time interval tFW, connecting the first and second terminals of the inductor together while the second terminal of the inductor is disconnected from the capacitor and the output terminal; and (f) at the termination of the time interval tFW, disconnecting the first and second terminals of the inductor from each other. - View Dependent Claims (40, 41, 42)
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43. A method of converting a DC input voltage to a DC output voltage comprising:
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(a) during a time interval tON, applying the DC input voltage to a first terminal of an inductor while coupling a second terminal of the inductor to a circuit ground so as to provide an inductor current through the inductor; (b) at the termination of the time interval tON, disconnecting the second terminal of the inductor from the circuit ground; (c) during a time interval tXFER, coupling the second terminal of the inductor to a capacitor and an output terminal so as to provide the DC output voltage at the output terminal and to provide a load current to a load connected to the output terminal; (d) at the termination of the time interval tXFER, disconnecting the second terminal of the inductor from the capacitor and the output terminal; (e) during a time interval tFW, connecting the first and second terminals of the inductor together while the second terminal of the inductor is disconnected from the capacitor and the output terminal; and (f) at the termination of the time interval tFW, disconnecting the first and second terminals of the inductor from each other; repeating (a)-(f) in the same sequence multiple times, wherein a level of the inductor current remains above a level of the load current during all of said time intervals.
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Specification