Power converter with controller operable in selected modes of operation

• US 8,692,532 B2
• Filed: 11/04/2010
• Issued: 04/08/2014
• 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
• Assistant Examiner(s): Grubb, Matthew
• Application Number:
  US12/939,681
• Publication Number:
  US 20110101934A1
• Time in Patent Office: 1,251 Days
• Field of Search: 323/224, 323/284, 323/285, 323/283
• US Class Current: 323/284
• 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 up to an upper current threshold level and thereafter control a level of current of said first switch to a remnant current level, said remnant current level being controlled in accordance with a current through a resistor;

enable conduction of said second switch when controlling said level of current of said first switch; and

disable conduction of said second switch when a current associated with said second switch reaches a lower current threshold level.

2. The controller as recited in claim 1 wherein said controller is configured to:

alternately enable conduction of said first and second switches with primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during a switching cycle;

enable conduction of said first switch with said primary duty cycle of said switching cycle up to said upper current threshold level and thereafter control said level of current of said first switch;

enable conduction of said second switch with said complementary duty cycle of said switching cycle; and

disable conduction of said second switch when said current associated with said second switch reaches said lower current threshold level.

3. The controller as recited in claim 1 wherein said circuit is operable in another mode of operation when a switching cycle counter exceeds a predetermined count and said controller is configured to alternately enable conduction of said first and second switches with primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during a switching cycle.

4. The controller as recited in claim 1 wherein said circuit is operable in another mode of operation when a switching cycle counter exceeds a predetermined count and said controller is configured to alternately enable conduction of said first and second switches with primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during a switching cycle and control said level of current in said first switch when said second switch is substantially disabled to conduct.

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

6. The controller as recited in claim 5 wherein said circuit is operable to transition from said another mode of operation to said mode of operation when said output characteristic of said circuit is less than a lower output characteristic threshold level.

7. The controller as recited in claim 5 wherein said controller is configured to disable elements therein during said another mode of operation.

8. The controller as recited in claim 1 wherein said controller is configured to increment a switching cycle counter during each switching cycle of said circuit.

9. The controller as recited in claim 1 wherein said controller is configured to control said level of current of said first switch in accordance with an error amplifier and a current mirror.

10. The controller as recited in claim 1 wherein said controller comprises an external resistor configured to adjust at least one of said upper current threshold level and said lower current threshold level.

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 up to an upper current threshold level and thereafter controlling a level of current of said first switch to a remnant current level, a current through in accordance with a resistor;

enabling conduction of said second switch when controlling said level of current of said first switch; and

disabling conduction of said second switch when a current associated with said second switch reaches a lower current threshold level.

12. The method as recited in claim 11, further comprising:

alternately enabling conduction of said first and second switches with primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during a switching cycle;

enabling conduction of said first switch with said primary duty cycle of said switching cycle up to said upper current threshold level and thereafter controlling said level of current of said first switch;

enabling conduction of said second switch with said complementary duty cycle of said switching cycle; and

disabling conduction of said second switch when said current associated with said second switch reaches said lower current threshold level.

13. The method as recited in claim 11 wherein said circuit is operable in another mode of operation when a switching cycle counter exceeds a predetermined count, said method further comprising alternately enabling conduction of said first and second switches with primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during a switching cycle.

14. The method as recited in claim 11 wherein said circuit is operable in another mode of operation when a switching cycle counter exceeds a predetermined count, said method further comprising alternately enabling conduction of said first and second switches with primary and complementary duty cycles, respectively, in response to an output characteristic of said circuit during a switching cycle and controlling said level of current in said first switch when said second switch is substantially disabled to conduct.

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

16. The method as recited in claim 15 wherein said circuit is operable to transition from said another mode of operation to said mode of operation when said output characteristic of said circuit is less than a lower output characteristic threshold level.

17. The method as recited in claim 15 further comprising disabling elements during said another mode of operation.

18. The method as recited in claim 11 further comprising incrementing a switching cycle counter during each switching cycle of said circuit.

19. The method as recited in claim 11 further comprising controlling said level of current of said first switch in accordance with an error amplifier and a current mirror.

20. The method as recited in claim 11 further comprising adjusting at least one of said upper current threshold level and said lower current threshold level.