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US 8,134,403 B2Granted
Reduced current charge pump
AssigneeFairchild Semiconductor Corporation
InventorsTimothy Alan Dhuyvetter, Brian Ben North, Cary L. Delano
Life of this patent
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Abstract
This document discusses, among other things, a charge pump having a plurality of switching devices, coupled in parallel, and configured to selectively provide a variable available drive current for a capacitor using a comparison of an output voltage to at least one reference voltage.
Claims20
A charge pump comprising:
- a flying capacitor configured to be switched between at least two states, wherein the flying capacitor is configured to provide the output voltage from an input voltage;
- a plurality of switching devices coupled in parallel between the input voltage and the flying capacitor, the plurality of switching devices configured to selectively provide a variable available drive current to the flying capacitor;
- a first comparator configured to compare the output voltage to a first reference voltage and to provide a first feedback signal using the comparison;
- a second comparator configured to compare the output voltage to a second reference voltage and to provide a second feedback signal using the comparison;
- a logic circuit configured to select at least one of the plurality of switching devices to provide the variable available drive current to the flying capacitor, wherein the logic circuit selects the at least one of the plurality of switching devices using the first and second feedback signals from the first and second comparators, wherein the variable available drive current is configured to vary depending on the selected at least one of the plurality of switching devices;
- and
- wherein the plurality of switching devices include binary devices having an ON state and an OFF state, the binary devices configured to provide a discrete magnitude of available drive current in the ON state and an insignificant magnitude of available drive current in the OFF state.
4 more elements
A method for providing an output voltage from a flying capacitor, the method comprising:
- receiving an input voltage at a plurality of switching devices;
- providing a variable available drive current to the flying capacitor using at least one of the plurality of switching devices;
- providing the output voltage with the flying capacitor;
- comparing the output voltage with at least one reference voltage;
- providing at least one feedback signal using the comparison;
- and
- selecting the at least one of the plurality of switching devices using the feedback signal, wherein the variable available drive current varies depending on the selected at least one of the plurality of switching devices;
- wherein the selecting the at least one of the plurality of switching devices includes increasing the available drive current when the output voltage is below the second reference voltage;
- and
- wherein the providing the output voltage using the at least one of the plurality of switching devices includes using a binary weighted current source, and wherein the increasing the available drive current includes increasing the number of switching devices used to provide the output voltage.
7 more elements
A circuit for providing an output voltage, the circuit comprising:
- a flying capacitor configured to be coupled between at least two states, wherein the flying capacitor is configured to provide the output voltage from an input voltage;
- a binary weighted current source including a plurality of switching devices coupled in parallel between the input voltage and the flying capacitor, the plurality of switching devices configured to provide charge from the input voltage to the flying capacitor, wherein at least one of the plurality of switching devices is configurable into an ON state and OFF state such that differing current is available to be provided to the flying capacitor depending on whether the at least one switching device is in the ON state or OFF state;
- a first comparator configured to compare the output voltage to a first reference voltage and provide a first feedback signal using the output voltage, wherein the first reference voltage includes a desired output voltage;
- a second comparator configured to compare the output voltage to a second reference voltage and provide a second feedback signal using the output voltage, wherein the second reference voltage includes a high output voltage threshold;
- a third comparator configured to compare the output voltage to a third reference voltage and provide a third feedback signal using the output voltage, wherein the third reference voltage includes a low output voltage threshold;
- and
- a logic circuit configured to select at least one of the plurality of switching devices to provide the input voltage to the flying capacitor using the feedback signal from the first, second, and third comparators.
4 more elements
A charge pump comprising:
- a flying capacitor configured to be switched between at least two states, wherein the flying capacitor is configured to provide the output voltage from an input voltage;
- a plurality of switching devices coupled in parallel between the input voltage and the flying capacitor, the plurality of switching devices configured to selectively provide a variable available drive current to the flying capacitor;
- a first comparator configured to compare the output voltage to a first reference voltage and to provide a first feedback signal using the comparison;
- a second comparator configured to compare the output voltage to a second reference voltage and to provide a second feedback signal using the comparison;
- a logic circuit configured to select at least one of the plurality of switching devices to provide the variable available drive current to the flying capacitor, wherein the logic circuit selects the at least one of the plurality of switching devices using the first and second feedback signals from the first and second comparators, wherein the variable available drive current is configured to vary depending on the selected at least one of the plurality of switching devices;
- wherein the first reference voltage and the second reference voltage include bounds for the output voltage and the first reference voltage is higher than the second reference voltage;
- wherein the first comparator is configured to provide a high signal when the output voltage is above the first reference voltage;
- and
- wherein the logic circuit is configured to change the selected at least one of the plurality of switching devices to decrease the available drive current in response to the high signal.
6 more elements
Dependencies are inferred from the claim text.