Methods and apparatus for DC-DC converter having independent outputs

• US 7,851,940 B2
• Filed: 10/31/2006
• Issued: 12/14/2010
• Est. Priority Date: 11/01/2005
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Mahin, Mir, Humenick, John, Wekhande, Shashank
• Primary Examiner(s): KAPLAN, HAL IRA
• Application Number:
  US11/554,756
• Publication Number:
  US 20070097574A1
• Time in Patent Office: 1,505 Days
• Field of Search: 323/267, 323/268, 323/269, 323/270, 323/271, 323/272, 307/11
• US Class Current: 307/11
• CPC Class Codes: H02M 1/009 having two or more independently controlled outputs for DC-DC converter with intermediate AC H02M3/33561
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/60 Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED]

Abstract

A DC-DC converter includes independent first and second outputs to drive respective first and second loads from a common boost module. In one embodiment, a first linear regulator controls a first controlling device for the first output and a second linear regulator controls a second controlling device for the second output. The load requiring the higher voltage controls the boost module.

Claims

1. A DC-DC converter circuit, comprising:

a boost circuit to boost an input voltage;

a first output for coupling to a first load and a second output for coupling to a second load, the first and second outputs being coupled to and driven by the boost circuit, wherein the first and second outputs are independently enabled;

a boost loop control module directly coupled to the boost circuit to control voltage supplied to the first and second outputs based upon which of the first or second output requires a higher boost voltage;

a first feedback path for a first feedback signal from the first output and a second feedback path for a second feedback signal from the second output;

a switch matrix to provide the first and second feedback paths; and

a minimum select circuit to receive the first and second feedback signals for determining which of the first and second outputs requires a higher output voltage.

2. The circuit according to claim 1, wherein the boost circuit includes a first switching element having a conduction state controlled by the boost loop control module.

3. The circuit according to claim 2, further including a first controlling element coupled to the boost circuit and to the first output.

4. The circuit according to claim 3, further including a linear regulator to control a conduction state of the first controlling element.

5. The circuit according to claim 4, wherein the linear regulator drops voltage that exceeds a voltage level required by the first load.

6. The circuit according to claim 3, further including a second controlling element coupled to the second output, wherein second output is connected between boost output and second controlling element.

7. The circuit according to claim 6, further including a linear regulator to control a conduction state of the second controlling element.

8. The circuit according to claim 7, wherein the linear regulator drops voltage that exceeds a voltage level required by the second load.

9. The circuit according to claim 1, further including first and second load terminals to energize the first load, wherein the first load terminal is coupled to the first output and the second load terminal is coupled to ground.

10. A circuit, comprising:

a DC-DC converter, including

a boost circuit including an inductor, a diode and a first switching device;

a boost loop control module to control a conduction state of the first switching device, the boost loop control module directly coupled to the boost circuit;

a first controlling device coupled to the boost circuit;

a first output controlled by the first controlling device for driving a first load;

a second controlling device coupled to the boost circuit through a second output, the second output controlled by the second controlling device for driving a second load, the first and second outputs being independently enabled, wherein the boost loop control module controls the first switching device based upon which of the first and second outputs requires a higher voltage;

a linear regulator coupled to the first controlling element;

a first feedback path to provide feedback information for the first output voltage; and

a first switch to couple the first feedback path to an input of the linear regulator.

11. The circuit according to claim 10, further including a second feedback path to provide feedback information from the second output node and a second switch to couple the second feedback path to the input of the linear regulator.

12. The circuit according to claim 10, further including a linear regulator coupled to the second controlling element, the linear regulator dropping voltage to the second output that is in excess of what is required by the second load.

13. The circuit according to claim 10, further including a hysteresis circuit for feedback signals from the first and second outputs.

14. The circuit according to claim 13, wherein the hysteresis circuit includes circuitry to compare at least one of the feedback signals from the first and second outputs against 0.95 times a reference voltage.

15. The circuit according to claim 10 further including a time delay circuit to transfer control between the first output and the second output.

16. A circuit, comprising:

a DC-DC converter, including

a boost circuit including an inductor, a diode and a first switching device;

a boost loop control module to control a conduction state of the first switching device, the boost loop control module directly coupled to the boost circuit;

a first controlling device coupled to the boost circuit;

a first output controlled by the first controlling device for driving a first load;

a second controlling device coupled to the boost circuit through a second output, the second output controlled by the second controlling device for driving a second load, the first and second outputs being independently enabled, wherein the boost loop control module controls the first switching device based upon which of the first and second outputs requires a higher voltage; and

a first enable input to enable the first output and a second enable input to enable the second output.

17. A circuit, comprising:

a DC-DC converter, including

a boost circuit including an inductor, a diode and a first switching device;

a boost loop control module to control a conduction state of the first switching device, the boost loop control module directly coupled to the boost circuit;

a first controlling device coupled to the boost circuit;

a first output controlled by the first controlling device for driving a first load;

a second controlling device coupled to the boost circuit through a second output, the second output controlled by the second controlling device for driving a second load, the first and second outputs being independently enabled, wherein the boost loop control module controls the first switching device based upon which of the first and second outputs requires a higher voltage; and

a minimum select circuit for determining which of the first and second outputs requires a higher output voltage.

18. A method of providing a DC-DC converter circuit, comprising:

coupling a first output to a boost circuit having a first switching element;

coupling a second output to the boost circuit;

coupling the first switching element to a boost loop control module;

coupling the boost loop control module directly to the boost circuit;

coupling feedback paths from the first and second outputs to the boost loop control module; and

coupling first and second enable signal paths to an ON-OFF module coupled to the boost loop control module to independently enable the first and second outputs.

19. The method according to claim 18, further including providing the boost loop control module to control the first and second outputs based upon which of the first and second outputs requires a higher voltage.

20. The method according to claim 18, further including coupling a linear regulator to the first switching element.

21. A DC-DC converter circuit, comprising:

a boost circuit to boost an input voltage;

a first output for coupling to a first load and a second output for coupling to a second load, the first and second outputs being coupled to and driven by the boost circuit, wherein the first and second outputs are independently enabled; and

a boost loop control module coupled to the boost circuit to control voltage supplied to the first and second outputs based upon which of the first or second output requires a higher boost voltage, wherein the first output is a constant voltage output and the second output is a constant current output.

22. A DC-DC converter circuit, comprising:

a boost circuit to boost an input voltage;

a first output for coupling to a first load and a second output for coupling to a second load, the first and second outputs being coupled to and driven by the boost circuit, wherein the first and second outputs are independently enabled;

a boost loop control module directly coupled to the boost circuit to control voltage supplied to the first and second outputs based upon which of the first or second output requires a higher boost voltage, wherein the boost circuit includes a first switching element having a conduction state controlled by the boost loop control module;

a first controlling element coupled to the boost circuit and to the first output; and

a first device to control a conduction state of the first controlling element, wherein the first controlling element selectively operates as a pass transistor of a linear regulator and a switch.

23. The circuit according to claim 22, wherein the first controlling element is operative to:

act as a switch when only first output is enabled,

act as a switch when the first and second outputs are enabled and first output is greater than second output, and

act as a pass transistor of a linear regulator when the first and second outputs are enabled and first output is smaller than second output.