Method and apparatus to provide temporary peak power from a switching regulator

• US 20060098463A1
• Filed: 11/05/2004
• Published: 05/11/2006
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Matthews, David Michael Hugh, Polivka, William M., Baurle, Stefan
• Granted Patent: US 7,239,119 B2
• Time in Patent Office: Days
• US Class Current: 363/21.01
• 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

Various techniques directed to providing temporary peak power from a switching regulator are disclosed. In one aspect, a switching regulator includes a switch that is to be coupled between a power supply input and an energy transfer element of the power supply. A controller is coupled to be responsive to a feedback signal to be received from an output of the power supply. The controller is coupled to switch the switch in response to the feedback signal to regulate the output of the power supply. An oscillator is coupled to provide an oscillating signal to the controller to determine a maximum switching frequency of the switch. The oscillating signal is coupled to oscillate at a first frequency under a first moderate load condition at the power supply output. The oscillating signal is coupled to oscillate at a second frequency under a second peak load condition at the power supply output.

Claims

1. A switching regulator circuit, comprising:

a switch coupled between an input of the power supply and an energy transfer element of the power supply, the energy transfer element to be coupled between the input and an output of the power supply; and

a controller circuit coupled to a control terminal of the switch, the controller circuit coupled to receive a feedback signal representative of an output level of the power supply, the controller circuit to switch the switch on and off at a switching frequency to regulate the output level of the power supply, the controller having a maximum switching frequency that is substantially independent of the input of the power supply, the maximum switching frequency to be limited to a first switching frequency when the load does not exceed a moderate power level threshold value, the maximum switching frequency to be limited to a second switching frequency that is higher than the first switching frequency when the load is greater than the moderate power level threshold value.

2. The switching regulator circuit of claim 1 wherein the controller circuit is included in an integrated circuit.

3. The switching regulator circuit of claim 1 wherein the controller circuit and the switch are integrated on a monolithic integrated circuit.

4. The switching regulator circuit of claim 1 wherein the load at the power supply output is greater than the moderate power level threshold value for only substantially short time durations such that a temperature of the switching regulator does not substantially increase while the load at the power supply output is greater than the moderate power level threshold value.

5. The switching regulator circuit of claim 4 wherein the load at the power supply output is greater than the moderate power level threshold value at intervals that do not substantially increase the temperature of the switching regulator.

6. The switching regulator circuit of claim 1 wherein the controller circuit comprises a pulse width modulator coupled to the switch to regulate the output level of the power supply.

7. The switching regulator circuit of claim 1 wherein the controller disables the power switch during selected switching periods to regulate the output level of the power supply.

8. The switching regulator of claim 1 wherein the maximum switching frequency of the switch is adjusted in response to an external load demand signal coupled to be received by the controller circuit.

9. The switching regulator circuit of claim 1 wherein the controller circuit further includes a peak load detect circuit coupled to sense a current in the switch to adjust the maximum switching frequency of the switch.

10. The switching regulator of claim 4 wherein the controller circuit includes a time limit circuit coupled to limit a duration of time that the switch may be switched at the second switching frequency.

11. A switching regulator circuit, comprising:

a switch between an input of the power supply and an energy transfer element of the power supply, the energy transfer element to be coupled between the input and an output of the power supply; and

a controller circuit coupled to a control terminal of the switch, the controller circuit coupled to receive a feedback signal representative of an output level of the power supply, the controller circuit to switch the switch on and off to regulate the output level of the power supply as an output power varies, the controller circuit to have a first maximum switching frequency when the output power is below a moderate power threshold value, the controller circuit to have a second maximum switching frequency when the output power is above the moderate power threshold value.

12. The switching regulator circuit of claim 11 wherein a switching frequency of the switch is substantially constant when the output power is below the moderate power threshold value and above either a standby or no-load power threshold.

13. The switching regulator of claim 12 wherein the switching frequency is varied up to the second maximum switching frequency to regulate the output level when the output power is above the moderate power threshold level.

14. The switching regulator circuit of claim 12 wherein the substantially constant switching frequency is substantially equal to the first maximum switching frequency.

15. The switching regulator circuit of claim 11 wherein the controller circuit comprises a time limit circuit coupled to limit a period of time for which the controller has the second maximum switching frequency.

16. The switching regulator circuit of claim 11 wherein the controller disables the power switch during selected switching periods to regulate the output level of the power supply.

17. A switching regulator, comprising:

a switch to be coupled between a power supply input and an energy transfer element of the power supply;

a pulse width modulator coupled to be responsive to a feedback signal to be received from an output of the power supply, the pulse width modulator to switch the switch in response to the feedback signal to regulate the output of the power supply;

an oscillator coupled to provide an oscillating signal to the pulse width modulator to determine a maximum switching frequency of the switch, the oscillating signal coupled to oscillate at a first frequency under a first moderate load condition at the power supply output, the oscillating signal coupled to oscillate at a second frequency under a second peak load condition at the power supply output.

18. The switching regulator of claim 17 wherein the first load condition occurs when a power supply output load is less than a first moderate load threshold value, the second load condition occurs when the power supply output load is greater than a second load threshold value.

19. The switching regulator of claim 17 further comprising a current limit circuit coupled to the switch and the pulse width modulator, the current limit circuit coupled to limit a current though the switch.

20. The switching regulator of claim 17 wherein the oscillator is coupled to receive a frequency shift signal to indicate whether to oscillate at the first frequency or the second frequency.

21. The switching regulator of claim 20 wherein the frequency shift signal is responsive to an external load demand signal coupled to be received by the switching regulator.

22. The switching regulator of claim 19 further comprising a peak load detect circuit coupled to the current limit circuit, the peak load detect circuit coupled to detect a peak load condition in response to the current limit circuit.

23. The switching regulator of claim 17 further comprising a time limit circuit coupled to the oscillator to limit a duration of time that the oscillating signal may oscillate at the second frequency.

24. The switching regulator of claim 17 wherein the second load condition occurs substantially less frequently than the first load condition.

25. The switching regulator of claim 17 wherein the second frequency is greater than the first frequency.

26. A method for regulating a power supply output, comprising:

receiving a feedback signal representative of an output level of a power supply output;

switching a switch in response to the feedback signal to regulate the flow of energy from an input of the power supply the power supply output;

detecting a peak load condition of a load at the power supply output; and

temporarily increasing a maximum switching frequency of the switch during the detected peak load condition.

27. The method of claim 26 wherein switching the switch in response to the feedback signal to regulate the flow of energy from the power supply input to the power supply output comprises pulse width modulating a control signal driving the switch.

28. The method of claim 26 further comprising detecting a current through the switch.

29. The method of claim 28 further comprising limiting the current through the switch to an amount below a current limit threshold.

30. The method of claim 28 further comprising detecting the peak load condition in response to the detected current through the switch.

31. The method of claim 26 further comprising identifying the peak load condition in response to an external load demand signal.

32. The method of claim 26 wherein temporarily increasing the maximum switching frequency of the switch during the detected peak load condition includes limiting a time duration that the switch may be switched at up to the increased maximum switching frequency.