Method and apparatus for a switch mode power supply that generates a high pulse width modulation gain while maintaining low noise sensitivity

• US 7,068,022 B2
• Filed: 11/12/2002
• Issued: 06/27/2006
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu
• Primary Examiner(s): Laxton, Gary L
• Application Number:
  US10/293,369
• Publication Number:
  US 20030090253A1
• Time in Patent Office: 1,323 Days
• Field of Search: 363/21.09, 363/21.17, 323/283, 323/284, 323/285
• US Class Current: 323/285
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence
• 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
• CPC Class Codes: H02M 3/338 in a self-oscillating arrangement H02M3/337 takes precedence

Abstract

A power supply with high pulse width modulation gain and low noise sensitivity has been disclosed. In one embodiment, a power supply includes a regulator circuit controlling a power switch. The regulator circuit includes a control input that receives a current, which is the sum of a consumption current of the regulator and a feedback current. The consumption current of the regulator is varied as a function of the duty cycle of the power switch. The feedback current is the current in a shunt regulator, which is control current in excess of the internal consumption of the regulator.

Claims

1. A regulator circuit, comprising:

a control terminal regulator circuit including a control terminal coupled to receive a control current that includes a feedback current and a consumption current of the regulator circuit; and

a power switch control circuit coupled to the control terminal regulator circuit and to a control terminal of a power switch, the power switch control circuit adapted to adjust a duty cycle at which the power switch is switched in response to the feedback current, wherein the consumption current of the regulator circuit is increased during an on-time of the power switch in response to the duty cycle at which the power switch is switched.

2. The regulator circuit of claim 1 wherein the control terminal regulator circuit includes a shunt regulator coupled to the control terminal, wherein a shunt regulator current of the shunt regulator is derived from the control current that exceeds the consumption current, wherein the feedback current is derived from the shunt regulator current.

3. The regulator circuit of claim 1 consumption current of the regulator circuit is increased in response to an increase in the duty cycle at which the power switch is switched.

4. The regulator circuit of claim 1 consumption current of the regulator circuit is decreased in response to a decrease in the duty cycle at which the power switch is switched.

5. The regulator circuit of claim 1 wherein the regulator circuit and the power switch are integrated on a monolithic chip.

6. The regulator circuit of claim 1 wherein the power switch includes a metal oxide semiconductor field effect transistor (MOSFET).

7. The regulator circuit of claim 1 wherein the power switch includes a bipolar junction transistor.

8. The regulator circuit of claim 1 further comprising a resistor coupled between the control terminal of the power switch and a ground terminal.

9. The regulator circuit of claim 1 further comprising a current source coupled between the control terminal of the power switch and a ground terminal.

10. The regulator circuit of claim 1 wherein the regulator circuit is included in a switching power supply.

11. The regulator circuit of claim 1 wherein the regulator circuit is included in a switching power supply with an approximately constant output voltage and output current characteristic.

12. A regulator circuit, comprising:

a power switch coupled between first and second terminals;

a control terminal regulator circuit including a control terminal coupled to receive an control current, the control current including a consumption current of the regulator circuit and a feedback current; and

a power switch control circuit coupled to the control terminal regulator circuit and a control terminal of the power switch, the power switch control circuit adapted to control a duty cycle of the power switch in response to the feedback current, the consumption current of the regulator circuit increased during an on-time of the power switch in response to the duty cycle of the power switch.

13. The regulator circuit of claim 12 further comprising a current path between a ground terminal of the regulator circuit and a control terminal of the power switch through which a portion of the consumption current is directed when the power switch is on.

14. The regulator circuit of claim 13 further comprising a resistor included along the current path between the ground terminal of the regulator circuit and the control terminal of the power switch.

15. The regulator circuit of claim 13 further comprising a current source included along the current path between the ground terminal of the regulator circuit and the control terminal of the power switch.

16. The regulator circuit of claim 12 further comprising a charging circuit coupled to the control terminal regulator circuit, the charging circuit and control terminal regulator circuit adapted to maintain the control terminal of the control terminal regulator circuit at a level set by the control terminal regulator circuit.

17. The regulator circuit of claim 12 wherein the control terminal regulator circuit includes a shunt regulator coupled to the control terminal of the control terminal regulator circuit, the shunt regulator to derive the feedback current from the control current that exceeds the consumption current of the regulator circuit.

18. The regulator circuit of claim 12 wherein the regulator circuit is included in a switching power supply, wherein the feedback current is proportional to an output level of the power supply.

19. The regulator circuit of claim 12 wherein regulator circuit is adapted to regulate the power supply output to have an approximately constant output voltage and output current characteristic.

20. The regulator circuit of claim 12 wherein the power switch control circuit includes pulse width modulation (PWM) circuitry to adjust the duty cycle of the power switch, the PWM circuitry having a PWM gain that is increased in response to an increase in the consumption current of the regulator circuit.

21. The regulator circuit of claim 20 the PWM circuitry operates in voltage mode.

22. The regulator circuit of claim 20 wherein the PWM circuitry operates in current mode.

23. The regulator circuit of claim 20 wherein the PWM circuitry operates in voltage mode or current mode depending upon whether the power supply output is operating in approximately constant voltage or approximately constant current region of the power supply output characteristic.

24. A regulator circuit, comprising:

a control terminal regulator circuit including a control terminal coupled to receive a control current that includes a feedback current and a subtraction current of the regulator circuit; and

a power switch control circuit coupled to the control terminal regulator circuit and to a control terminal of a power switch, the power switch control circuit adapted to adjust a duty cycle at which the power switch is switched in response to the feedback current, wherein the subtraction current of the regulator circuit is increased during an on-time of the power switch in response to the duty cycle at which the power switch is switched.

25. The regulator circuit of claim 24 wherein the control terminal regulator circuit includes a shunt regulator coupled to the control terminal, wherein a shunt regulator current of the shunt regulator is derived from the control current that exceeds the subtraction current, wherein the feedback current is derived from the shunt regulator current.

26. The regulator circuit of claim 24 subtraction current of the regulator circuit is increased response increase in the duty cycle at which the power switch is switched.

27. The regulator circuit of claim 24 subtraction current of the regulator circuit is decreased in response to a decrease in the duty cycle at which the power switch is switched.

28. The regulator circuit of claim 24 wherein the regulator circuit and the power switch are integrated on a monolithic chip.

29. The regulator circuit of claim 24 wherein the power switch includes a metal oxide semiconductor field effect transistor (MOSFET).

30. The regulator circuit of claim 24 the power switch includes a bipolar junction transistor.

31. The regulator circuit of claim 24 further comprising a resistor coupled between the control terminal of the power switch and a ground terminal.

32. The regulator circuit of claim 24 further comprising a current source coupled between the control terminal of the power switch and a ground terminal.

33. The regulator circuit of claim 24 wherein the regulator circuit is included a switching power supply.

34. The regulator circuit of claim 24 wherein the regulator circuit is included a switching power supply with an approximately constant output voltage and output current characteristic.

35. A regulator circuit, comprising:

a control terminal regulator circuit including a control terminal coupled to receive an input signal that includes a feedback signal and a subtraction signal of the regulator circuit; and

a power switch control circuit coupled to the control terminal regulator circuit and to a control terminal of a power switch, the power switch control circuit adapted to adjust a duty cycle at which the power switch is switched in response to the feedback signal, wherein the subtraction signal of the regulator circuit is increased during an on-time of the power switch in response to the duty cycle at which the power switch is switched.

36. The regulator circuit of claim 35 subtraction signal of the regulator circuit is increased in response to an increase in the duty cycle at which the power switch is switched.

37. The regulator circuit of claim 35 subtraction of the regulator circuit is decreased in response to a decrease in the duty cycle at which the power switch is switched.

38. The regulator circuit of claim 35 wherein the regulator circuit and the power switch are integrated on a monolithic chip.

39. The regulator circuit of claim 35 wherein the power switch includes a metal oxide semiconductor field effect transistor (MOSFET).

40. The regulator circuit of claim 35 wherein switch includes a bipolar junction transistor.

41. The regulator circuit of claim 35 further comprising a resistor coupled between an ON signal of the power switch and a ground terminal.

42. The regulator circuit of claim 35 further comprising a signal source coupled between an ON signal of the power switch and a ground terminal.

43. The regulator circuit of claim 35 wherein the regulator circuit is included a switching power supply.

44. The regulator circuit of claim 35 wherein the regulator circuit is included a switching power supply with an approximately constant output voltage and output signal characteristic.