Integrated on-time extension for non-dissipative bleeding in a power supply

• US 8,299,730 B2
• Filed: 02/09/2010
• Issued: 10/30/2012
• Est. Priority Date: 02/09/2010
• Status: Expired due to Fees

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Gaknoki, Yury, Mao, Mingming, Pastore, Tiziano
• Primary Examiner(s): Le, Tung X
• Application Number:
  US12/703,072
• Publication Number:
  US 20110193494A1
• Time in Patent Office: 994 Days
• Field of Search: 315/291, 315/294, 315/297, 315/307, 315/308, 315/360, 363/16, 363/20, 363/21.01, 363/21.12, 363/21.17, 363/21.18, 363/56.11, 363/95, 363/97, 363/131, 323/282, 323/284
• US Class Current: 315/307
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H02M 5/2573 with control circuit
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• 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

An example controller for a switched mode power supply includes a zero-crossing detector, drive logic, and an on-time extension block. The zero-crossing detector is coupled to generate a first signal prior to a zero-crossing of an input voltage of the power supply. The drive logic is to generate a drive logic output signal in response to a feedback signal, where the drive logic output signal is representative of an initial on-time. The on-time extension block is coupled to the zero-crossing detector and to the drive logic to generate a drive signal in response to the drive logic output signal. The drive signal controls switching of a switch to remove charge from a filter capacitor of the power supply. The drive signal is representative of a total on-time of the switch equal to a sum of the initial on-time and an extended on-time, where the extended on-time is responsive to the first signal.

Claims

1. A controller for a switched mode power supply, the controller comprising:

a zero-crossing detector coupled to generate a first signal prior to a zero-crossing of an input voltage of the power supply;

a drive logic to be coupled to generate a drive logic output signal in response to a feedback signal representative of an output of the power supply, wherein the drive logic output signal is representative of an initial on-time; and

an on-time extension block coupled to the zero-crossing detector and the drive logic to generate a drive signal in response to the drive logic output signal, the drive signal to control switching of a switch to be coupled to the controller to remove charge from a filter capacitor of the power supply, wherein the drive signal is representative of a total on-time of the switch equal to a sum of the initial on-time and an extended on-time, wherein the extended on-time is responsive to the first signal.

2. The controller of claim 1, wherein the first signal is a pre-condition signal to indicate whether a pre-condition exists for the zero-crossing of the input voltage of the power supply.

3. The controller of claim 2, wherein the on-time extension block is adapted to increase the extended on-time of the switch until the pre-condition signal indicates that the pre-condition no longer exists or until the total on-time reaches a zero-crossing time threshold.

4. The controller of claim 3, wherein the on-time extension block is coupled to receive a zero-crossing pulse signal that includes a time period representative of the zero-crossing time threshold.

5. The controller of claim 1, wherein the zero-crossing detector generates the first signal in response to the input voltage of the power supply being less than a zero-crossing voltage threshold.

6. The controller of claim 1, wherein the zero-crossing detector generates the first signal in response to a switch current flowing through the switch being less than a zero-crossing current threshold.

7. The controller of claim 1, wherein the zero-crossing detector is coupled to generate a zero-crossing signal to indicate that a zero-crossing condition exists and wherein the drive logic generates the drive logic output signal in response to the zero-crossing signal and the feedback signal.

8. The controller of claim 1, wherein the controller and the switch are included in an integrated circuit.

9. The controller of claim 1, wherein the controller is an integrated circuit controller for a switched mode power supply.

10. A controller for a switched mode power supply, the controller comprising:

a zero-crossing detector coupled to generate a first signal prior to a zero-crossing of an input voltage of the power supply;

a drive logic to be coupled to generate a drive logic output signal in response to a feedback signal representative of an output of the power supply, wherein the drive logic output signal is representative of an initial on-time; and

an on-time extension block having a latch to generate a drive signal to control switching of the switch included in the power supply, wherein the latch is coupled to be set in response to the drive logic output signal and wherein the drive signal is to control switching of a switch to be coupled to the controller to remove charge from a filter capacitor of the power supply, wherein the drive signal is representative of a total on-time of the switch equal to a sum of the initial on-time and an extended on-time, wherein the extended on-time is responsive to the first signal.

11. The controller of claim 10, wherein the first signal is a pre-condition signal to indicate whether a pre-condition exists for the zero-crossing of the input voltage of the power supply.

12. The controller of claim 11, wherein the latch is coupled to be reset if either the pre-condition signal indicates that the pre-condition no longer exists or if the total on-time reaches a zero-crossing time threshold.

13. The controller of claim 12, wherein the latch is further coupled to be reset in response to the drive logic output signal.

14. The controller of claim 10, wherein the on-time extension block is coupled to receive a zero-crossing pulse signal that includes a time period representative of the zero-crossing time threshold.

15. The controller of claim 10, wherein the zero-crossing detector generates the first signal in response to the input voltage of the power supply being less than a zero-crossing voltage threshold.

16. The controller of claim 10, wherein the zero-crossing detector generates the first signal in response to a switch current flowing through the switch being less than a zero-crossing current threshold.

17. The controller of claim 10, wherein the zero-crossing detector is coupled to generate a zero-crossing signal to indicate that a zero-crossing condition exists and wherein the drive logic generates the drive logic output signal in response to the zero-crossing signal and the feedback signal.

18. The controller of claim 10, wherein the controller and the switch are included in an integrated circuit.

19. The controller of claim 10, wherein the controller is an integrated circuit controller for a switched mode power supply.

20. A switched mode power supply, comprising:

a switch;

an energy transfer element coupled to the switch and coupled to generate an output in response to an input voltage;

a filter capacitor coupled across the energy transfer element and the switch; and

a controller coupled to regulate the output in response to the input voltage, wherein the controller includes;

a zero-crossing detector coupled to generate a first signal prior to a zero-crossing of the input voltage;

a drive logic to be coupled to generate a drive logic output signal in response to a feedback signal representative of an output of the power supply, wherein the drive logic output signal is representative of an initial on-time; and

an on-time extension block coupled to the zero-crossing detector and the drive logic to generate a drive signal in response to the drive logic output signal, the drive signal to control switching of a switch to be coupled to the controller to remove charge from the filter capacitor to pull down a voltage on the filter capacitor such that the voltage on the filter capacitor substantially follows a magnitude of the input voltage, wherein the drive signal is representative of a total on-time of the switch equal to a sum of the initial on-time and an extended on-time, wherein the extended on-time is responsive to the first signal.

21. The power supply of claim 20, further comprising a dimmer circuit coupled between the energy transfer element and an input of the power supply to control an amount of time the input voltage is disconnected from the energy transfer element to dim the input voltage.

22. The power supply of claim 21 wherein the dimmer circuit is a triac dimmer circuit.

23. The power supply of claim 22, wherein the triac dimmer circuit includes a minimum holding current to keep the triac dimmer circuit from turning off and wherein the on-time extension block is configured to maintain a current through the triac dimmer circuit such that the current through the triac dimmer circuit does not fall below the minimum holding current.

24. The power supply of claim 20, wherein the output of the power supply is to be coupled to a load that includes an array of light emitting diodes.

25. The power supply of claim 20, wherein the first signal is a pre-condition signal to indicate whether a pre-condition exists for the zero-crossing of the input voltage of the power supply.

26. The power supply of claim 25, wherein the on-time extension block is adapted to increase the extended on-time of the switch until the pre-condition signal indicates that the pre-condition no longer exists or until the total on-time reaches a zero-crossing time threshold.

27. The power supply of claim 20, wherein the on-time extension block is coupled to receive a zero-crossing pulse signal that includes a time period representative of the zero-crossing time threshold.

28. The power supply of claim 20, wherein the zero-crossing detector generates the first signal in response to the input voltage of the power supply being less than a zero-crossing voltage threshold.

29. The power supply of claim 20, wherein the zero-crossing detector generates the first signal in response to a switch current flowing through the switch being less than a zero-crossing current threshold.

30. The power supply of claim 20, wherein the zero-crossing detector is coupled to generate a zero-crossing signal to indicate that a zero-crossing condition exists and wherein the drive logic generates the drive logic output signal in response to the zero-crossing signal and the feedback signal.

31. The power supply of claim 20, wherein the controller and the switch are included in an integrated circuit.

32. The power supply of claim 20, wherein the controller is an integrated circuit controller.