System and method for controlling output signal of power converter

1. A method for controlling a power converter, the method comprising:

generating a first gain control signal and a second gain control signal in response to a gain transition signal, the gain transition signal indicating a transition of the power converter from a first gain mode to a second gain mode, a time interval in the first gain mode including a transient period and a steady state period;

entering the first gain mode in response to the first gain control signal; and

entering the second gain mode in response to the second gain control signal,

wherein the first gain mode is a proportional gain mode and the second gain mode is an integral gain mode.

2. The method of claim 1 , further comprising increasing a value of a tracking signal during the transient period of the first gain mode, the tracking signal indicating an output signal of the power converter,

wherein the tracking signal is settled to proximate to a specific value during the steady state period of the first gain mode.

3. The method of claim 2 , further comprising:

generating a feedback signal in response to the tracking signal and a reference signal;

comparing a value of the feedback signal to a value of a threshold signal; and

entering from the transient period to the steady state period when a comparison result is obtained from comparing the value of the feedback signal to the value of the threshold signal.

4. The method of claim 1 , further comprising:

generating a feedback signal in response to a tracking signal and a reference signal, the tracking signal indicating an output signal of the power converter; and

generating the gain transition signal that has a specific logic value in response to the feedback signal, the specific logic value indicating the transition from the first gain mode to the second gain mode.

5. The method of claim 4 , further comprising:

generating a transition setting signal in response to the feedback signal and a threshold signal;

generating the second gain control signal in response to the transition setting signal and the gain transition signal; and

inverting the second gain control signal to generate the first gain control signal.

6. The method of claim 4 , further comprising:

generating a reference feedback signal in response to the feedback signal;

comparing a value of the reference feedback signal to a value of the feedback signal to generate an output signal; and

generating the gain transition signal in response to the output signal.

7. The method of claim 1 , further comprising:

generating the gain transition signal that has a specific logic value in response to an input signal of the power converter, the specific logic value indicating the transition from the first gain mode to the second gain mode.

8. The method of claim 7 , further comprising:

synchronizing the gain transition signal with the input signal of the power converter to generate an output signal having the specific logic value at a first given time relative to a second given time of the input signal of the power converter, the second given time corresponding to a predetermined value of the input signal.

9. The method of claim 7 , further comprising:

detecting a slope of the input signal of the power converter to generate the gain transition signal having the specific logic value.

10. A circuit for controlling a power converter comprising:

a gain transition controller configured to generate a first gain control signal and a second gain control signal in response to a gain transition signal, the gain transition signal indicating a transition of the power converter from a first gain mode to a second gain mode, a time interval in the first gain mode including a transient period and a steady state period; and

a gain control circuit configured to generate a feedback signal in response to the first gain control signal and the second gain control signal, the power converter increasing a value of an output signal during the transient period of the first gain mode in response to the feedback signal.

11. The circuit of claim 10 , wherein the first gain mode is a proportional gain mode and the second gain mode is an integral gain mode.

12. The circuit of claim 10 , wherein a tracking signal indicates the output signal of the power converter, and the tracking signal is settled to proximate to a specific value during the steady state period of the first gain mode.

13. The circuit of claim 12 , wherein the gain control circuit includes an amplifier generating the feedback signal in response to the tracking signal and a reference signal, and

wherein the gain transition controller includes a comparator comparing a value of the feedback signal to a value of a threshold signal.

14. The circuit of claim 10 , wherein the gain control circuit includes an amplifier generating the feedback signal in response to a tracking signal and a reference signal, and

wherein the gain transition controller includes a transition signal generator generating the gain transition signal that has a specific logic value in response to the feedback signal, the specific logic value indicating of the transition from the first gain mode to the second gain mode.

15. The circuit of claim 14 , wherein the gain transition controller further includes:

a transition setting circuit generating a transition setting signal in response to the feedback signal and a threshold signal,

a gain control signal generator generating the second gain control signal in response to the transition setting signal and the gain transition signal; and

an inverter inverting the second gain control signal to generate the first gain control signal.

16. The circuit of claim 14 , wherein the transition signal generator includes:

a reference feedback signal generator generating a reference feedback signal in response to the feedback signal;

a comparator comparing a value of the reference feedback signal to a value of the feedback signal to generate an output signal; and

an edge trigger generating the gain transition signal in response to the output signal.

17. The circuit of claim 10 , wherein the gain transition controller includes a transition signal generator generating the gain transition signal that has a specific logic value in response to an input signal of the power converter, the specific logic value indicating the transition from the first gain mode to the second gain mode.

18. The circuit of claim 17 , wherein the transition signal generator includes:

a synchronizing circuit generating an output signal having the specific logic high value at a first given time relative to a second given time of the input signal of the power converter, the second given time corresponding to a predetermined value of the input signal.

19. The circuit of claim 10 , wherein the gain transition controller includes a transition signal generator asserting the gain transition signal in response to any one of an average value of the feedback signal, a slope of the feedback signal, a slope of an input signal of the power converter, a maximum value of the input signal, and a minimum value of the input signal.

20. The circuit of claim 10 , further comprising a modulation controller configured to generate a modulation signal in response to the feedback signal.

21. The circuit of claim 20 , wherein the modulation controller reduces one or both of an on-time duration and a switching frequency of the modulation signal when a value of the feedback signal is decreased, and

wherein the modulation controller increases one or both of the on-time duration and the switching frequency of the modulation signal when a value of the feedback signal is increased.