Switching controller for resonant power converter

• US 7,313,004 B1
• Filed: 12/21/2006
• Issued: 12/25/2007
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: System General Corporation (ON Semiconductor Corporation)
• Inventors: Yang, Ta-Yung, Lin, Chien-Yuan, Shih, Kuang-Chih, Wang, Wei-Ting
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US11/614,971
• Time in Patent Office: 369 Days
• Field of Search: 363/16, 363/21.02, 363/21.03, 363/39, 363/40, 363/41, 363/56.01, 363/95, 363/97
• US Class Current: 363/21.02
• 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: H02M 3/3376 with automatic control of output voltage or current
• 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 integrated control circuit for a resonant power converter includes a minimum-frequency programming circuit connected a first resistor to program a minimum switching frequency of the power converter. A feedback circuit is coupled to a feedback terminal to receive a feedback signal for generating an adjustment signal. A maximum-frequency programming circuit connects a second resistor to determine a maximum switching frequency in response to the adjustment signal. An oscillator is coupled to the minimum-frequency programming circuit and the maximum-frequency programming circuit to generate an oscillation signal for determining the switching frequency of the power converter. A feed-forward circuit is connected to a feed-forward terminal to receive a feed-forward signal represents the input voltage of the power converter. The switching frequency is increased in response to decrease of the feedback signal, and the switching frequency is increased in response to the increase of the feed-forward signal.

Claims

1. A switching controller of a resonant power converter, comprising:

a feedback circuit coupled to a feedback terminal to receive a feedback signal for generating an adjustment signal;

a minimum-frequency programming circuit coupled to a minimum-frequency programming terminal to generate a first current signal for determining a minimum switching frequency of the power converter;

a maximum-frequency programming circuit coupled to a maximum-frequency programming terminal to generate a second current signal in response to the adjustment signal to determine a maximum switching frequency of the power converter; and

an oscillation circuit generating an oscillation signal in response to the first signal and the second signal;

wherein the oscillation signal determines a switching frequency of the power converter.

2. The switching controller as claimed in claim 1, further comprising:

a feed-forward circuit coupled to a feed-forward terminal to receive a feed-forward signal representing an input voltage of the power converter;

wherein the feed-forward signal is coupled to modulate the switching frequency of the power converter.

3. The switching controller as claimed in claim 1, wherein the switching frequency is increased in response to decrease of the feedback signal, and the switching frequency is increased in response to the increase of the feed-forward signal.

4. The switching controller as claimed in claim 1, further comprising:

a soft-start circuit coupled to a soft-start terminal to receive a soft-start signal;

wherein the soft-start signal is coupled to program the adjustment signal.

5. The switching controller as claimed in claim 1, further comprising:

a power management circuit coupled to a power-level programming terminal to receive a power-level signal for generating a burst signal;

wherein the burst signal is generated once the feedback signal is lower than a light-load threshold;

the light-load threshold is determined by the power-level signal;

the burst signal is coupled to on/off a switching signal of the power converter.

6. The switching controller as claimed in claim 5, in which the burst signal is linearly modulated in response to the change of the load of the power converter.

7. The switching controller as claimed in claim 5, wherein an enable time of the burst signal is fixed and a disable time of the burst signal is modulated in response to the change of the feedback signal.

8. The switching controller as claimed in claim 5, wherein the burst signal is disabled when frequency of the burst signal is between a first frequency and a second frequency.

9. The switching controller as claimed in claim 1, further comprising:

a monitoring circuit coupled to a protection input terminal to generate an over-voltage signal; and

a time-delay circuit coupled to initiate a first time delay in response to the over-voltage signal;

wherein the over-voltage signal is generated when voltage of the protection input terminal is higher than an over-voltage threshold;

the time-delay circuit generates a protection signal to disable the switching signal of the power converter once the first time delay is expired.

10. The switching controller as claimed in claim 9, in which the time delay circuit initiates a second time delay once the protection signal is generated;

the protection signal is reset once the second time delay is expired;

wherein the period of the second time delay is longer than the period of the first time delay.

11. A switching control circuit of a power converter, comprising:

a feedback circuit coupled to a feedback terminal to receive a feedback signal for generating an adjustment signal;

a minimum-frequency programming circuit coupled to generate a first signal for determining a minimum switching frequency of the power converter;

a maximum-frequency programming circuit coupled to generate a second signal in response to the adjustment signal to determine a maximum switching frequency of the power converter;

a feed-forward circuit coupled to receive a feed-forward signal representing the input voltage of the power converter; and

an oscillation circuit generating an oscillation signal in response to the first signal and the second signal;

wherein the feed-forward signal is coupled to modulate the oscillation signal;

the oscillation signal determines a switching frequency of the power converter.

12. The switching control circuit as claimed in claim 11, wherein the switching frequency is increased in response to decrease of the feedback signal;

the switching frequency is increased in response to the increase of the feed-forward signal.

13. The switching control circuit as claimed in claim 11, further comprising:

a power management circuit coupled to generate a burst signal;

wherein the burst signal is coupled to on/off a switching signal of the power converter;

the burst signal is generated once the feedback signal is lower than a light-load threshold;

in which an enable time of the burst signal is fixed and a disable time of the burst signal is modulated in response to the change of the feedback signal.

14. The switching control circuit as claimed in claim 13, wherein the burst signal is disabled when the frequency of the burst signal is operated between a first frequency and a second frequency.

15. The switching control circuit as claimed in claim 11, further comprising:

a monitoring circuit coupled to a protection input terminal to generate an over-voltage signal; and

a time-delay circuit coupled to initiate a first time delay in response to the over-voltage signal;

wherein the over-voltage signal is generated when the voltage of the protection input terminal is higher than an over-voltage threshold; and

the time-delay circuit generates a protection signal to disable a switching signal of the power converter once the first time delay is expired.

16. The switching control circuit as claimed in claim 15, in which the time delay circuit initiates a second time delay once the protection signal is generated;

the protection signal is reset once the second time delay is expired;

wherein the period of the second time delay is longer than the period of the first time delay.

17. A control circuit of a power converter, comprising:

a feedback circuit coupled to a feedback terminal to receive a feedback signal for generating an adjustment signal;

a minimum-frequency programming circuit coupled to generate a first signal for determining a minimum switching frequency of the power converter;

a maximum-frequency programming circuit coupled to generate a second signal in response to the adjustment signal to determine a maximum switching frequency of the power converter;

an oscillation circuit generating an oscillation signal in response to the first signal and the second signal; and

a power management circuit coupled to generate a burst signal in response to the feedback signal;

wherein the oscillation signal determines a switching frequency of the power converter; and

the burst signal is coupled to on/off a switching signal of the power converter.

18. The control circuit as claimed in claim 17, wherein the burst signal is generated once the feedback signal is lower than a light-load threshold;

in which an enable time of the burst signal is fixed and a disable time of the burst signal is modulated in response to the change of the feedback signal;

the burst signal is disabled when the frequency of the burst signal is between a first frequency and a second frequency.

19. The control circuit as claimed in claim 17, further comprising:

a feed-forward circuit coupled to receive a feed-forward signal representing the input voltage of the power converter;

wherein the feed-forward signal is coupled to modulate the switching frequency of the power converter.

20. The control circuit as claimed in claim 19, wherein the switching frequency is increased in response to decrease of the feedback signal;

the switching frequency is increased in response to the increase of the feed-forward signal.

21. The control circuit as claimed in claim 17, further comprising:

a monitoring circuit coupled to a protection input terminal to generate an over-voltage signal; and

a time-delay circuit coupled to initiate a first time delay in response to the over-voltage signal;

wherein the over-voltage signal is generated when the voltage of the protection input terminal is higher than an over-voltage threshold;

the time-delay circuit generates a protection signal to disable the switching signal of the power converter once the first time delay is expired.

22. The control circuit as claimed in claim 21, in which the time delay circuit initiates a second time delay once the protection signal is generated;

the protection signal is reset once the second time delay is expired;

wherein the period of the second time delay is longer than the period of the first time delay.