VOLTAGE CONVERTER

• US 20130321374A1
• Filed: 05/29/2013
• Published: 12/05/2013
• Est. Priority Date: 05/31/2012
• Status: Abandoned Application

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Farenc, Didier H.
• Application Number:
  US13/904,583
• Publication Number:
  US 20130321374A1
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

This disclosure provides systems, methods and apparatus for voltage conversion. In one aspect, a voltage converter includes a first feedback loop monitoring one of two converter outputs of opposite polarity. The converter may further include a second feedback loop for monitoring a weighted sum of the two converter outputs of opposite polarity. In another aspect, a voltage converter may include level shifters for driving switches coupled to a boost inductor. The voltage converter may switch at least one voltage rail coupled to the level shifters from a first voltage level to a second voltage level.

Claims

1. A voltage converter comprising:

first and second voltage outputs of opposite polarity;

an inductor;

a first switch having an input coupled to a first inductor rail voltage and an output coupled to an input of the inductor;

a second switch having an input coupled to an output of the inductor and an input coupled to a second inductor rail voltage;

a first level shifter having an output coupled to the first switch to control the on/off state of the first switch and having one or more inputs coupled to one or more level shifter rail voltages;

a second level shifter having an output coupled to the second switch to control the on/off state of the second switch and having one or more inputs coupled to the one or more level shifter rail voltages;

control circuitry coupled to the first and second level shifters;

a first feedback loop configured to provide an indication of the output voltage at one of the first and second voltage outputs to the control circuitry; and

a second feedback loop configured to provide an indication of a weighted sum of the first and second output voltages to the control circuitry.

2. The voltage converter of claim 1, wherein the first and second voltage outputs have a magnitude of 20 V or more.

3. The voltage converter of claim 2, wherein the one or more level shifter rail voltages are 16 V or less.

4. The voltage converter of claim 1, additionally comprising a switching circuit for switching the level shifter rail voltages from one voltage level to a second voltage level during operation of the voltage converter.

5. The voltage converter of claim 1, wherein the first feedback loop is configured to compare the output voltage at one of the first or second voltage outputs to a reference voltage.

6. The voltage converter of claim 5, wherein the second feedback loop is configured to compare the average of the first and second output voltages to ground.

7. A display apparatus comprising the voltage converter of claim 1.

8. The display apparatus of claim 7, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

9. The display apparatus of claim 8, further comprising:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

10. The display apparatus of claim 8, further comprising:

an image source module configured to send the image data to the processor, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

11. The display apparatus of claim 8, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

12. The display apparatus of claim 8, wherein the display comprises electromechanical display elements.

13. A method of operating a voltage converter having at least one pair of outputs of opposite polarity, the method comprising:

monitoring an output voltage at one of the outputs of the pair;

monitoring a weighted sum of the output voltages of the pair of outputs; and

determining which output to boost based at least in part on the output voltage at one of the outputs and the weighted sum.

14. The method of claim 13, wherein monitoring an output voltage at one of the outputs of the pair includes comparing the output voltage at one of the outputs of the pair to a reference voltage.

15. The method of claim 13, wherein monitoring the average output voltage of the pair of outputs includes comparing the average output voltage of the pair of outputs to ground.

16. A voltage converter comprising:

means for boosting a pair of voltage outputs having opposite polarity;

means for monitoring an output voltage at one of the outputs of the pair;

means for monitoring a weighted sum of the output voltages of the pair of outputs; and

control circuitry for determining which output to boost based at least in part on the output voltage at one of the outputs and the weighted sum.

17. The voltage converter of claim 16, wherein the means for boosting includes an inductor.

18. The voltage converter of claim 16, wherein the means for monitoring an output voltage at one of the outputs of the pair includes a comparator.

19. The voltage converter of claim 16, wherein the means for monitoring the average output voltage of the pair of outputs includes a comparator.

20. A voltage converter comprising:

first and second voltage outputs of opposite polarity;

an inductor;

a first switch having an input coupled to a first inductor rail voltage and an output coupled to an input of the inductor;

a second switch having an input coupled to an output of the inductor and an input coupled to a second inductor rail voltage;

a first level shifter having an output coupled to the first switch to control the on/off state of the first switch and having one or more inputs coupled to one or more level shifter rail voltages;

a second level shifter having an output coupled to the second switch to control the on/off state of the second switch and having one or more inputs coupled to one or more level shifter rail voltages;

control circuitry coupled to the first and second level shifters;

a switch circuit configured to switch at least one level shifter rail voltage from one voltage level to a second voltage level during operation of the voltage converter.

21. The voltage converter of claim 20, wherein the first and second voltage outputs have a magnitude of 20 V or more.

22. The voltage converter of claim 21, wherein the one or more level shifter rail voltages are 16 V or less.

23. The voltage converter of claim 20, wherein the switch circuit is configured to switch a level shifter rail voltage from an inductor rail voltage to a voltage output.

24. A display apparatus comprising the voltage converter of claim 20.

25. The display apparatus of claim 24, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

26. The display apparatus of claim 25, further comprising:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

27. The display apparatus of claim 25, further comprising:

an image source module configured to send the image data to the processor, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

28. The display apparatus of claim 25, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

29. The display apparatus of claim 25, wherein the display comprises electromechanical display elements.

30. A method of operating a voltage converter having at least one pair of outputs of opposite polarity, the method comprising:

driving a level shifter with a first rail voltage; and

switching from driving the level shifter with the first rail voltage to a second rail voltage different from the first rail voltage.

31. The method of claim 30, comprising driving a boost inductor with the first rail voltage.

32. The method of claim 30, wherein the second rail voltage is a voltage converter output.

33. A voltage converter comprising:

means for boosting a pair of voltage outputs having opposite polarity;

means for driving a level shifter with a first rail voltage; and

means for switching from driving the level shifter with the first rail voltage to a second rail voltage different from the first rail voltage.

34. The voltage converter of claim 33, wherein the means for boosting includes an inductor.

35. The voltage converter of claim 34, further comprising means for driving the inductor with the first rail voltage.

36. The voltage converter of claim 35, wherein the means for switching includes means for switching the level shifter rail voltage to an output voltage of the voltage converter.