Power converter with controller operable in selected modes of operation

• US 8,541,991 B2
• Filed: 11/04/2010
• Issued: 09/24/2013
• 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): BERHANE, ADOLF D
• Application Number:
  US12/939,639
• Publication Number:
  US 20110101933A1
• Time in Patent Office: 1,055 Days
• Field of Search: 323/224, 323/284, 323/285, 323/283
• US Class Current: 323/224
• 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 until an output characteristic of said circuit exceeds an upper output characteristic threshold level and thereafter control a level of current of said first switch;

enable conduction of said second switch; and

disable conduction of said second switch when said output characteristic crosses a lower output characteristic 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 said output characteristic of said circuit during a switching cycle;

enable conduction of said first switch with said primary duty cycle of said switching cycle until said output characteristic of said circuit exceeds said upper output characteristic 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 and terminate said switching cycle when said output characteristic crosses said lower output characteristic threshold level.

3. The controller as recited in claim 1 wherein said circuit is operable in another mode of operation when a time exceeds a predetermined time.

4. The controller as recited in claim 3 wherein said predetermined time is about 600 microseconds beginning from a time when said circuit enters said mode of operation.

5. The controller as recited in claim 1 wherein said circuit is operable in another mode of operation when a time exceeds a predetermined time 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.

6. The controller as recited in claim 1 wherein said circuit transitions to said mode of operation when a switching cycle counter exceeds a predetermined count.

7. The controller as recited in claim 1 wherein said circuit is operable in another mode of operation and said controller is 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;

enable conduction of said second switch; and

disable conduction of said second switch when a current associated with said second switch reaches a lower current threshold level, wherein said circuit transitions from said another mode of operation to said mode of operation when a switching cycle counter exceeds a predetermined count.

8. The controller as recited in claim 7 wherein at least one of said upper current threshold level and said lower current threshold level is fixed.

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 output characteristic is an output voltage of said circuit, said upper output characteristic threshold level is an upper output voltage threshold level and said lower output characteristic threshold level is a lower output voltage 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 until an output characteristic of said circuit exceeds an upper output characteristic threshold level and thereafter controlling a level of current of said first switch;

enabling conduction of said second switch; and

disabling conduction of said second switch when said output characteristic crosses a lower output characteristic 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 said output characteristic of said circuit during a switching cycle;

enabling conduction of said first switch with said primary duty cycle of said switching cycle until said output characteristic of said circuit exceeds said upper output characteristic 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 and terminating said switching cycle when said output characteristic crosses said lower output characteristic threshold level.

13. The method as recited in claim 11 wherein said circuit is operable in another mode of operation when a time exceeds a predetermined time.

14. The method as recited in claim 13 wherein said predetermined time is about 600 microseconds beginning from a time when said circuit enters said mode of operation.

15. The method as recited in claim 11 wherein said circuit is operable in another mode of operation when a time exceeds a predetermined time, 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.

16. The method as recited in claim 11 wherein said circuit transitions to said mode of operation when a switching cycle counter exceeds a predetermined count.

17. The method as recited in claim 11 wherein said circuit is operable in another mode of operation and said method, further comprises:

enabling conduction of said first switch up to an upper current threshold level and thereafter controlling a level of current of said first switch;

enabling conduction of said second switch; and

disabling conduction of said second switch when a current associated with said second switch reaches a lower current threshold level, wherein said circuit transitions from said another mode of operation to said mode of operation when a switching cycle counter exceeds a predetermined count.

18. The method as recited in claim 17 wherein at least one of said upper current threshold level and said lower current threshold level is fixed.

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 wherein said output characteristic is an output voltage of said circuit, said upper output characteristic threshold level is an upper output voltage threshold level and said lower output characteristic threshold level is a lower output voltage threshold level.