Off-line converter with digital control

• US 6,414,471 B1
• Filed: 08/10/2001
• Issued: 07/02/2002
• Est. Priority Date: 02/27/1998
• Status: Expired due to Term

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu, Lund, Leif O., Djenguerian, Alex B.
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US09/927,273
• Publication Number:
  US 20020024328A1
• Time in Patent Office: 326 Days
• Field of Search: 323/282, 323/283, 323/284, 323/285, 363/16, 363/18, 363/19, 363/20, 363/97, 363/131
• US Class Current: 323/283
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence

Abstract

A DC to DC converter comprising an energy storage element comprising an energy storage element input and an energy storage element output, the energy storage element input coupled to receive a first power level and the energy storage element output providing a second power level. The converter also comprises a feedback circuit comprising a feedback input and a feedback output, the feedback input coupled to the energy storage element output. The converter further comprises a regulator circuit comprising a regulator circuit feedback input and a regulator circuit output, the regulator circuit feedback input coupled to the feedback output and the regulator circuit output coupled to the energy storage element input, the regulator circuit regulating the input of the first power level to the energy storage element input. When a signal at the regulator circuit feedback input is above a threshold level the regulator circuit ceasing operation and when the signal at the regulator circuit feedback input is below the threshold level the regulator circuit is enabled.

Claims

1. A circuit for regulating the level at a power converter output, the circuit comprising:

an input for receiving a feedback signal, the feedback signal having a first feedback state that represents a level that is above a threshold level and a second feedback state that represents a level that is below the threshold level;

an oscillator that provides a duty cycle signal that cycles between two states; and

a switch including a first terminal, a second terminal and a control terminal, said switch being operable to couple or decouple the first terminal and the second terminal in response to a control signal received at the control terminal, the control signal being responsive to the duty cycle signal and to a change between the first and second feedback states.

2. The circuit of claim 1 wherein the control signal responds substantially instantaneously to a change between the first and second feedback states.

3. The circuit of claim 1 wherein the control signal is capable of responding to a change between the first and second feedback states at any point in a cycle of the duty cycle signal.

4. The circuit of claim 1 wherein the control signal does not respond to a change from the second feedback state to the first feedback state until after the completion of the current state of the duty cycle signal.

5. The circuit of claim 1 wherein the circuit is operable to respond to a change from the second feedback state to the first feedback state to halt the cycling of the duty cycle signal.

6. The circuit of claim 5 wherein the circuit is operable to respond to a change from the first feedback state to the second feedback state to substantially instantaneously restart the cycling of the duty cycle signal.

7. The circuit of claim 1 wherein the switch comprises a transistor.

8. The circuit of claim 1 wherein the level at the power converter output is a voltage level or a current level.

9. The circuit of claim 1 wherein the circuit further comprises a monolithic device.

10. The circuit of claim 1 further comprising a bypass output, a capacitor coupled to the bypass output and a current source coupled between the first terminal of the switch and the bypass output.

11. The circuit of claim 10 wherein the current source provides current to charge the capacitor when the switch does not couple the first terminal and the second terminal.

12. A circuit coupled between a power converter input and a power converter output for regulating the level at the power converter output, comprising:

a switch for selectively enabling or disabling the flow of energy between the power converter input and the power converter output;

an input for receiving a feedback signal, the feedback signal having a first feedback state that represents a level at the power converter output that is above a threshold level and a second feedback state that represents a level at the power converter output that is below the threshold level; and

an oscillator that provides a duty cycle signal that cycles between two states,

the circuit operable to control said switch in response to the duty cycle signal and to the feedback signal to enable the flow of energy from the power converter input to the power converter output if the feedback signal is in the second feedback state and disable the flow of energy from the power converter input to the power converter output if the feedback signal is in the first feedback state.

13. The circuit of claim 12 wherein the circuit is operable to control said switch substantially instantaneously after a change between the first and second feedback states.

14. The circuit of claim 12 wherein the circuit is operable to control said switch in response to a change between the first and second feedback states at any point in a cycle of the duty cycle signal.

15. The circuit of claim 12 wherein the circuit is operable to control said switch to not respond to a change from the second feedback state to the first feedback state until after the completion of the current state of the duty cycle signal.

16. The circuit of claim 12 wherein the circuit is operable to respond to a change from the second feedback state to the first feedback state to halt the cycling of the duty cycle signal.

17. The circuit of claim 16 wherein the circuit is operable to respond to a change from the first feedback state to the second feedback state to substantially instantaneously restart the cycling of the duty cycle signal.

18. The circuit of claim 12 wherein the circuit further comprises a monolithic device.

19. A method of regulating the level at a power converter output, said power converter having a power converter input and the power converter output, said method comprising:

receiving a feedback signal, the feedback signal having a first feedback state that represents a level at the power converter output that is above a threshold level and a second feedback state that represents a level at the power converter output that is below the threshold level;

providing a duty cycle signal that cycles between two states; and

in response to the duty cycle signal and to a change between the first and second feedback states, enabling or disabling the flow of energy from the power converter input to the power converter output.

20. The method of claim 19 wherein the flow of energy from the power converter input to the power converter output circuit is enabled or disabled substantially instantaneously after a change between the first and second feedback states.

21. The method of claim 19 wherein the flow of energy from the power converter input to the power converter output may be enabled or disabled at any point in a cycle of the duty cycle signal.

22. The method of claim 19 wherein the flow of energy from the power converter input to the power converter output is not disabled in response to a change from the second feedback state to the first feedback state until after the completion of the current state of the duty cycle signal.

23. The method of claim 19 wherein, in response to a change from the second feedback state to the first feedback state, the cycling of the duty cycle signal is halted.

24. The method of claim 23 wherein, substantially instantaneously in response to a change from the first feedback state to the second feedback state, the cycling of the duty cycle signal is restarted.

25. A power converter, comprising:

a power converter input and a power converter output;

a regulation circuit coupled between the power converter input and the power converter output;

a feedback signal, the feedback signal having a first feedback state that represents a level at the power converter output that is above a threshold level and a second feedback state that represents a level at the power converter output that is below the threshold level; and

an oscillator that provides a duty cycle signal that cycles between two states,

the regulation circuit being operable to respond to the duty cycle signal and to a change between the first and second feedback states to enable or disable the flow of energy from the power converter input to the power converter output.

26. The power converter of claim 25 wherein the regulation circuit is operable to enable or disable the flow of energy from the power converter input to the power converter output substantially instantaneously after a change between the first and second feedback states.

27. The power converter circuit of claim 25 wherein the regulation circuit is operable to enable or disable the flow of energy from the power converter input to the power converter output in response to a change between the first and second feedback states at any point in a cycle of the duty cycle signal.

28. The power converter of claim 25 wherein the regulation circuit is operable to not disable the flow of energy from the power converter input to the power converter output in response to a change from the second feedback state to the first feedback state until after the completion of the current state of the duty cycle signal.

29. The power converter of claim 25 wherein the regulation circuit is operable to disable the flow of energy from the power converter input to the power converter output within one cycle of the duty cycle signal after a change from the second feedback state to the first feedback state.

30. The power converter of claim 25 wherein the regulation circuit is operable to respond to a change from the second feedback state to the first feedback state to halt the cycling of the duty cycle signal.

31. The power converter of claim 30 wherein the regulation circuit is operable to respond to a change from the first feedback state to the second feedback state to substantially instantaneously restart the cycling of the duty cycle signal.

32. The power converter of claim 25 wherein the regulation circuit further comprises a monolithic device.

33. The power converter of claim 25 further comprising a transformer and wherein the regulation circuit is operable to enable or disable the flow of energy from the power converter input through the transformer to the power converter output.

34. The power converter of claim 25 further comprising an energy storage element and wherein the regulation circuit is operable to enable or disable the flow of energy from the power converter input to the energy storage element and from the energy storage element to the power converter output.