Power converter with controller operable in selected modes of operation

• US 8,686,698 B2
• Filed: 11/04/2010
• Issued: 04/01/2014
• Est. Priority Date: 04/16/2008
• Status: Active Grant

• Current Assignee: Altera Corporation (Intel Corporation)
• Original Assignee: Enpirion, Inc. (MediaTek, Inc.)
• Inventors: Lopata, Douglas Dean, Lotfi, Ashraf W.
• Primary Examiner(s): Behm, Harry
• Application Number:
  US12/939,530
• Publication Number:
  US 20110101948A1
• Time in Patent Office: 1,244 Days
• Field of Search: 323/283, 323/224, 323/282
• US Class Current: 323/224
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power converter and method of controlling the same for selected modes of operation. In one embodiment, the power converter includes a first power switch coupled to a source of electrical power and a second power switch coupled to the first power switch and to an output terminal of the power converter. The power converter also includes a controller configured to control an operation of the first and second power switches during selected modes of operation.

Claims

1. A controller for use with a circuit having first and second switches operable in a mode of operation, configured to:

enable conduction of said first switch with a primary duty cycle of a switching cycle; and

enable conduction of said second switch with a complementary duty cycle of said switching cycle, wherein said primary duty cycle is set to a maximum value and said complementary duty cycle is limited to a minimum value during said switching cycle when a switching cycle counter exceeds a predetermined count.

2. The controller as recited in claim 1 wherein said controller is configured to alternately enable conduction of said first and second switches with said primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during said switching cycle.

3. The controller as recited in claim 1 wherein said controller is configured to control a level of current of said first switch during said complementary duty cycle.

4. The controller as recited in claim 1 wherein said controller is configured to set said primary duty cycle to said maximum value and limit said complementary duty cycle to said minimum value during said switching cycle to facilitate detection of a reverse or low level of current flow associated with said second switch.

5. The controller as recited in claim 1 wherein said controller is configured to periodically limit said complementary duty cycle during said switching cycle.

6. The controller as recited in claim 1 wherein said predetermined count corresponds to 64 switching cycles.

7. The controller as recited in claim 1 wherein said circuit is operable in another mode of operation when a current associated with said second switch is less than a current threshold level and said controller is configured to alternately enable conduction of said first and second switches with said primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during said switching cycle and control a level of current of said first switch when said alternately enabling conduction of said first and second switched is disabled.

8. The controller as recited in claim 7 wherein said controller is configured to disable elements therein during said another mode of operation.

9. The controller as recited in claim 7 wherein said controller is configured to adjust said current threshold level in accordance with a direct current level of an output current of said circuit.

10. The controller as recited in claim 9 wherein said direct current level of said output current is set by a resistor divider network including an external resistor.

11. A method for use with a circuit having first and second switches operable in a mode of operation, comprising:

enabling conduction of said first switch with a primary duty cycle of a switching cycle; and

enabling conduction of said second switch with a complementary duty cycle of said switching cycle, wherein said primary duty cycle is set to a maximum value and said complementary duty cycle is limited to a minimum value during said switching cycle when a switching cycle counter exceeds a predetermined count.

12. The method as recited in claim 11 further comprising alternately enabling conduction of said first and second switches with said primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during said switching cycle.

13. The method as recited in claim 11 further comprising controlling a level of current of said first switch during said complementary duty cycle.

14. The method as recited in claim 11 wherein setting said primary duty cycle to said maximum value and limiting said complementary duty cycle to said minimum value during said switching cycle facilitates detection of a reverse or low level of current flow associated with said second switch.

15. The method as recited in claim 11 further comprising periodically limiting said complementary duty cycle during said switching cycle.

16. The method as recited in claim 11 wherein said predetermined count corresponds to 64 switching cycles.

17. The method as recited in claim 11 wherein said circuit is operable in another mode of operation when a current associated with said second switch is less than a current threshold level, said method further comprising alternately enabling conduction of said first and second switches with said primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during said switching cycle and controlling a level of current of said first switch when said alternately enabling conduction of said first and second switched is disabled.

18. The method as recited in claim 17 further comprising disabling elements during said another mode of operation.

19. The method as recited in claim 17 further comprising adjusting said current threshold level in accordance with a direct current level of an output current of said circuit.

20. The method as recited in claim 19 wherein said direct current level of said output current is set by a resistor divider network including an external resistor.