Method and Apparatus for a Charge Pump DC-to-DC Converter Having Parallel Operating Modes

• US 20090016085A1
• Filed: 07/11/2007
• Published: 01/15/2009
• Est. Priority Date: 07/11/2007
• Status: Active Grant

• Current Assignee: Semtech Corporation
• Original Assignee: Semtech Corporation
• Inventors: Rader, Bill, Keesor, David P., Perkins, Calbert Lee
• Granted Patent: US 7,808,220 B2
• Time in Patent Office: Days
• US Class Current: 363/79
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

According to one or more aspects of DC-to-DC voltage conversion as taught herein, a DC-to-DC converter selectively operates in a first mode wherein an included linear pass output circuit supplies the output power from the DC-to-DC converter, in a second mode wherein an included charge pump output circuit supplies the output power, and in a third mode wherein the linear pass and charge pump output circuits operate in parallel to supply the output power. With this third mode, also referred to as a “dual” mode, wherein the linear pass and charge pump output circuits operate in parallel, the DC-to-DC converter keeps the more efficient output circuit on after it has begun switching to operation with the less efficient output circuit. Such switchover may be performed dynamically in response to changing operating conditions. Detected operating conditions may include input voltages, output voltages, and output load conditions.

Claims

1. A method of operating a DC-to-DC converter that includes a linear pass output circuit and a charge pump output circuit, the method comprising:

in a first mode of operation, supplying output power via the linear pass output circuit;

in a second mode of operation, supplying the output power via the charge pump output circuit;

in a third mode of operation, supplying the output power via the linear pass and charge pump output circuits operating in parallel; and

dynamically switching between the first, second, and third modes of operation based on one or more detected operating conditions.

2. The method of claim 1, wherein dynamically switching between the first, second, and third modes of operation based on one or more detected operating conditions includes selecting the third mode of operation if the one or more detected operating conditions indicate that a more efficient one of the linear pass and charge pump output circuits can supply some but not all of the output power from the DC-to-DC converter.

3. The method of claim 2, wherein dynamically switching between the first, second, and third modes of operation based on one or more detected operating conditions includes selecting one of the first and second modes that corresponds to the more efficient one of the linear pass and charge pump output circuits if the detected operating conditions indicate that the more efficient one can supply all of the output power from the DC-to-DC converter.

4. The method of claim 2, wherein dynamically switching between the first, second, and third modes of operation based on one or more detected operating conditions includes selecting the first mode of operation if the detected operating conditions indicate that the charge pump output circuit cannot supply any of the output power from the DC-to-DC converter, or selecting the second mode of operation if the detected operating conditions indicate that the linear pass output circuit cannot supply any of the output power from the DC-to-DC converter.

5. The method of claim 1, further comprising, while in the third mode of operation, operating a stronger one of the linear pass and charge pump output circuits as a regulated voltage source and operating a weaker one of the linear pass and charge pump output circuits as an unregulated voltage source.

6. The method of claim 5, further comprising exiting the third mode of operation responsive to detecting that operating the linear pass and charge pump output circuits in parallel is interfering with regulating an output voltage of the DC-to-DC converter.

7. The method of claim 5, further comprising exiting the third mode in response to detecting that an input voltage of the DC-to-DC converter is at or below a threshold that prevents one of the linear pass and charge pump output circuits from continuing to supply any output power.

8. The method of claim 1, wherein one of the linear pass and charge pump output circuits is a stronger but less efficient output circuit and the other one is a weaker but more efficient output circuit, and wherein dynamically switching between the first, second, and third modes of operation based on one or more detected operating conditions includes selecting the third mode of operation if detected operating conditions indicate that the weaker but more efficient one of the linear pass and charge pump output circuits can supply some but not all of the output power from the DC-to-DC converter.

9. The method of claim 8, further comprising, while in the third mode of operation, operating the stronger output circuit with voltage regulation and operating the weaker output circuit without voltage regulation.

10. The method of claim 8, further comprising exiting the third mode of operation responsive to detecting that operation in the third mode interferes with regulation of the output voltage of the DC-to-DC converter.

11. The method of claim 8, further comprising exiting the third mode of operation responsive to detecting that an input voltage of the DC-to-DC converter is at or below a threshold for allowing continued operation of the weaker output circuit.

12. A DC-to-DC converter comprising:

a linear pass output circuit;

a charge pump output circuit; and

a control circuit configured to selectively operate the DC-to-DC converter in a first, second, or third mode, wherein in the first mode the linear pass output circuit supplies output power from the DC-to-DC converter, in the second mode the charge pump output circuit supplies the output power, and in the third mode the linear pass and charge pump output circuits operate in parallel to supply the output power.

13. The DC-to-DC converter of claim 12, wherein the control circuit is configured to select the third mode of operation if the one or more detected operating conditions indicate that a more efficient one of the linear pass and charge pump output circuits can supply some but not all of the output power from the DC-to-DC converter.

14. The DC-to-DC converter of claim 13, wherein the control circuit is configured to select one of the first and second modes that corresponds to the more efficient one of the linear pass and charge pump output circuits if the detected operating conditions indicate that the more efficient one can supply all of the output power from the DC-to-DC converter.

15. The DC-to-DC converter of claim 13, wherein the control circuit is configured to select the first mode of operation if the detected operating conditions indicate that the charge pump output circuit cannot supply any of the output power from the DC-to-DC converter, or to select the second mode of operation if the detected operating conditions indicate that the linear pass output circuit cannot supply any of the output power from the DC-to-DC converter.

16. The DC-to-DC converter of claim 12, wherein the control circuit is configured to, while in the third mode of operation, operate a stronger one of the linear pass and charge pump output circuits as a regulated voltage source and operate a weaker one of the linear pass and charge pump output circuits as an unregulated voltage source.

17. The DC-to-DC converter of claim 16, wherein the control circuit is configured to exit the third mode of operation responsive to detecting that operating the linear pass and charge pump output circuits in parallel is interfering with regulating an output voltage of the DC-to-DC converter.

18. The DC-to-DC converter of claim 16, wherein the control circuit is configured to exit the third mode in response to detecting that an input voltage of the DC-to-DC converter is at or below a threshold that prevents one of the linear pass and charge pump output circuits from continuing to supply any of the output power.

19. The DC-to-DC converter of claim 12, wherein one of the linear pass and charge pump output circuits is a stronger but less efficient output circuit and the other one is a weaker but more efficient output circuit, and wherein the control circuit is configured to select the third mode of operation if detected operating conditions indicate that the weaker but more efficient one of the linear pass and charge pump output circuits can supply some but not all of the output power from the DC-to-DC converter.

20. The DC-to-DC converter of claim 19, wherein the control circuit is configured to, while in the third mode of operation, operate the stronger output circuit with voltage regulation and operate the weaker output circuit without voltage regulation.

21. The DC-to-DC converter of claim 20, wherein the control circuit is configured to exit the third mode of operation responsive to detecting that operation in the third mode interferes with regulation of the output voltage of the DC-to-DC converter.

22. The DC-to-DC converter of claim 20, wherein the control circuit is configured to exit the third mode of operation responsive to detecting that an input voltage of the DC-to-DC converter is at or below a threshold for allowing continued operation of the weaker output circuit.

23. A method of operating a DC-to-DC converter that includes a linear pass output circuit and a charge pump output circuit, the method comprising for given output load conditions of the DC-to-DC converter:

providing output power from the DC-to-DC converter via the linear pass output circuit for a first range of input voltages to the DC-to-DC converter;

providing output power from the DC-to-DC converter via the charge pump output circuit for a second range of input voltages to the DC-to-DC converter; and

providing output power from the DC-to-DC converter via the parallel combination of the linear pass and charge pump output circuits for a third range of input voltages between the first and second ranges of input voltages.