METHOD AND APPARATUS FOR IMPLEMENTING AN UNREGULATED DORMANT MODE IN A POWER CONVERTER

• US 20090295346A1
• Filed: 05/29/2008
• Published: 12/03/2009
• Est. Priority Date: 05/29/2008
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Matthews, David Michael Hugh
• Granted Patent: US 7,952,895 B2
• Time in Patent Office: Days
• US Class Current: 323/267
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004
• CPC Class Codes: H02M 3/00 Conversion of dc power input into dc power output
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A control circuit for use in a power converter with an unregulated dormant mode of operation is disclosed. In one aspect a power converter includes a drive signal generator coupled to generate a drive signal to control switching of a power switch to be coupled to the control circuit to regulate a flow of energy to a power converter output in response to an energy requirement of one or more loads to be coupled to the power converter output. An unregulated dormant mode control circuit is included and is coupled to render dormant the drive signal generator thereby ceasing the regulation of the flow of energy to the power converter output by the drive signal generator when the energy requirement of the one or more loads falls below a threshold. The drive signal generator is coupled to be unresponsive to changes in the energy requirements of the one or more loads when dormant. The unregulated dormant mode control circuit is coupled to power up the drive signal generator after a period of time has elapsed. The drive signal generator is coupled to again be responsive to changes in the energy requirement of the one or more loads after the period of time has elapsed.

Claims

1. A control circuit for use in a power converter, comprising:

a drive signal generator coupled to generate a drive signal to control switching of a power switch to be coupled to the control circuit to regulate a flow of energy to a power converter output in response to an energy requirement of one or more loads to be coupled to the power converter output; and

an unregulated dormant mode control circuit coupled to render dormant the drive signal generator thereby ceasing the regulation of the flow of energy to the power converter output by the drive signal generator when the energy requirement of the one or more loads falls below a threshold, the drive signal generator coupled to be unresponsive to changes in the energy requirements of the one or more loads when dormant, the unregulated dormant mode control circuit coupled to power up the drive signal generator after a period of time has elapsed, the drive signal generator coupled to again be responsive to changes in the energy requirement of the one or more loads after the period of time has elapsed.

2. The control circuit of claim 1 wherein the energy requirements of the one or more loads is determined in response to a feedback signal coupled to be received by the control circuit.

3. The control circuit of claim 2 wherein the energy requirements of the one or more loads is determined in response to a magnitude of the feedback signal coupled to be received by the control circuit.

4. The control circuit of claim 3 wherein the magnitude of the feedback signal is a voltage value.

5. The control circuit of claim 3 wherein the magnitude of the feedback signal is a current value.

6. The control circuit of claim 1 wherein the energy requirements of the one or more loads is determined in response to a switching frequency of the drive signal.

7. The control circuit of claim 1 wherein the power converter is a flyback converter.

8. The control circuit of claim 1 wherein the period of time is determined by a capacitor to be coupled to the control circuit.

9. The control circuit of claim 8 wherein the capacitor to be coupled to the control circuit comprises an external bypass capacitor for the control circuit.

10. The control circuit of claim 8 further comprising a regulator circuit to be coupled to charge the capacitor in response to the unregulated dormant mode control circuit, the regulator circuit coupled to not charge the capacitor when the energy requirements of the one or more loads falls below the threshold and to again charge the capacitor after the period of time has elapsed.

11. The control circuit of claim 1 wherein the power switch comprises a metal oxide semiconductor field effect transistor (MOSFET).

12. The control circuit of claim 1 wherein the power switch comprises a bipolar transistor.

13. The control circuit of claim 1 wherein the power switch is coupled to regulate the flow of energy to the power converter output through an energy transfer element and the energy transfer element comprises an isolated output winding, wherein one of the one or more loads is coupled to the isolated output winding.

14. The control circuit of claim 13 wherein said one of the one or more loads comprises a preload impedance and a load coupled to output terminals of the power converter.

15. The control circuit of claim 1 wherein the power switch is coupled to regulate the flow of energy to the power converter output through an energy transfer element and the energy transfer element comprises a non-isolated sense winding, wherein one of the one or more loads is coupled to the non-isolated sense winding.

16. The control circuit of claim 1 wherein the power switch is coupled to regulate the flow of energy to the power converter output through an energy transfer element and the energy transfer element comprises a non-isolated bias winding, wherein one of the one or more loads is coupled to the non-isolated bias winding.

17. The control circuit of claim 1 wherein the power switch is coupled to regulate the flow of energy to the power converter output through an energy transfer element and the energy transfer element comprises an isolated output winding and a non-isolated bias winding, wherein one of the one or more loads is coupled to the isolated output winding and an other one of the one or more loads is coupled to the non-isolated bias winding.

18. The control circuit of claim 1 wherein the power switch is coupled to regulate the flow of energy to the power converter output through an energy transfer element and the energy transfer element comprises a non-isolated output winding, wherein one of the one or more loads comprises a combined sensing and bias load coupled to the non-isolated output winding.

19. The control circuit of claim 1 wherein the power switch is coupled to regulate the flow of energy to the power converter output through an energy transfer element and the energy transfer element comprises an isolated output winding and a non-isolated output winding, wherein one of the one of the one or more loads is coupled to the isolated output winding and an other one of the loads comprises a combined sensing and bias load coupled to the non-isolated output winding.

20. A method for controlling an output of a power converter, comprising:

generating a drive signal to regulate a flow of energy to one or more loads coupled to an output of the power converter in response to energy requirement of the one or more loads;

ceasing for a period of time the regulation of energy flow to the one or more loads when an energy requirement of the one or more loads falls below a threshold value;

not responding to the energy requirement of the one or more loads during the period of time; and

resuming after the period of time has elapsed the regulation of energy flow to the one or more loads.

21. The method of claim 20 wherein one of the loads is a sensing circuit coupled to the power converter output.

22. The method of claim 20 wherein one of the loads is a combined sense and bias circuit coupled to one of the power converter output.

23. The method of claim 20 wherein one of the loads is a preload impedance in combination with a load coupled to output terminals of the power converter.

24. The method of claim 23 wherein ceasing for the period of time the regulation of energy flow to the one or more loads comprises ceasing the flow of energy when energy requirements of the combined preload and load falls below the threshold value.

25. The method of claim 20 wherein one of the one or more loads is coupled to output terminals of the power converter.

26. The method of claim 25 wherein ceasing for the period of time the regulation of energy flow to the one or more loads comprises ceasing the flow of energy when the energy requirement of the one of the one or more loads that is coupled to output terminals of the power converter falls below the threshold value.

27. A control circuit for use in a power converter, comprising:

a feedback circuit coupled to detect an energy requirement of one or more loads to be coupled to the power converter output;

a drive signal generator coupled to generate a drive signal to control switching of a power switch to be coupled to the control circuit to regulate a flow of energy to the power converter output in response to the feedback circuit;

a timer coupled to determine a time period in response to the feedback circuit indicating that the energy requirement of the one or more loads has fallen below a threshold; and

an unregulated dormant mode control circuit coupled to the timer and coupled to render dormant the feedback circuit and the drive signal generator during the time period thereby causing regulation of the flow of energy to the power converter output to cease, the unregulated dormant mode control circuit further coupled to power up the feedback circuit and the drive signal generator after the time period has elapsed.

28. The control circuit of claim 27 wherein the drive signal generator and feedback circuit are coupled to be unresponsive to changes in the energy requirement of the one or more loads when dormant and again are responsive to changes in the energy requirements of the one or more loads after the time period has elapsed.

29. The control circuit of claim 27 wherein the unregulated dormant mode control circuit comprises a comparator coupled to the timer and a latch.

30. The control circuit of claim 27 wherein the unregulated dormant mode control circuit comprises a counter coupled to an oscillator and the feedback circuit to determine when the feedback circuit indicates that the energy requirement of the one or more loads has fallen below a threshold.

31. The control circuit of claim 27 the timer comprises an external bypass capacitor coupled to the control circuit.

32. A control circuit for use in a power converter, comprising:

a feedback circuit coupled to detect an energy requirement of one or more loads to be coupled to the power converter output;

a drive signal generator coupled to generate a drive signal to control switching of a power switch to be coupled to the control circuit to regulate a flow of energy to the power converter output in response to the feedback circuit;

a regulator circuit to be coupled to charge a capacitor, the capacitor to determine a time period, the regulator circuit coupled to not charge the capacitor in response to the feedback circuit indicating that the energy requirement of the one or more loads has fallen below a threshold and to again charge the capacitor after the time period has elapsed; and

an unregulated dormant mode control circuit coupled to render dormant the feedback circuit, the regulator circuit and the drive signal generator during the time period thereby causing regulation of the flow of energy to the power converter output to cease, the unregulated dormant mode control circuit further coupled to power up the feedback circuit, the regulator and the drive signal generator after the time period has elapsed.

33. The control circuit of claim 32 wherein the unregulated dormant mode control circuit comprises a comparator coupled to the capacitor and a latch.

34. The control circuit of claim 32 wherein the unregulated dormant mode control circuit comprises a counter coupled to an oscillator and the feedback circuit to determine when the feedback circuit indicates that the energy requirement of the one or more loads has fallen below a threshold.

35. The control circuit of claim 32 wherein the drive signal generator, regulator circuit and feedback circuit are coupled to be unresponsive to changes in the energy requirement of the one or more loads when dormant and again are responsive to changes in the energy requirements of the one or more loads after the time period has elapsed.

36. The control circuit of claim 32 wherein the capacitor comprises an external bypass capacitor to be coupled to the control circuit.