REGULATION CIRCUIT HAVING OUTPUT CABLE COMPENSATION FOR POWER CONVERTERS AND METHOD THEREOF

1 . A regulation circuit of a power converter, comprising:

an error amplifier generating a feedback signal in accordance with an output of the power converter; and

a compensation circuit coupled to a transformer of the power converter for generating a compensation signal in response to a transformer signal generated by the transformer;

wherein the feedback signal is applied to generate a switching signal for switching the transformer and regulating the output of the power converter; the compensation signal is coupled to modulate the feedback signal for compensating a voltage drop of an output cable of the power converter.

2 . The regulation circuit as claimed in claim 1 , wherein the error amplifier comprises a reference signal for generating the feedback signal; the compensation signal is coupled to compensate the reference signal for modulating the feedback signal.

3 . The regulation circuit as claimed in claim 1 , further comprising:

a resistor coupled to the compensation circuit for programming the level of the compensation signal.

4 . The regulation circuit as claimed in claim 1 , wherein the transformer signal is related to an on time of the switching signal and the level of an input voltage of the transformer.

5 . The regulation circuit as claimed in claim 1 , wherein the compensation signal is generated in accordance with a demagnetizing time of the transformer.

6 . The regulation circuit as claimed in claim 1 , wherein the compensation signal is increased in response to the increase of an output current of the power converter; the feedback signal is increased in response to the increase of the compensation signal; an output voltage is increased in response to the increase of the feedback signal.

7 . The regulation circuit as claimed in claim 1 , wherein the regulation circuit is located in a secondary side of the transformer.

8 . The regulation circuit as claimed in claim 1 , wherein the compensation circuit comprises:

a capacitor providing a voltage for generating the compensation signal;

a charging current charging the capacitor in response to the transformer signal for providing the voltage, the charging current is correlated to the transformer signal; and

a voltage to current converter converting the voltage to the compensation signal;

wherein the transformer signal is related to an on time of the switching signal and the level of an input voltage of the transformer.

9 . A method for compensating an output cable of a power converter, comprising:

generating a feedback signal in accordance with an output of the power converter;

generating a compensation signal in response to a transformer signal generated by a transformer of the power converter; and

modulating the feedback signal by using the compensation signal;

wherein the feedback signal is utilized to generate a switching signal for switching the transformer of the power converter and regulating the output of the power converter; the compensation signal is coupled to compensate a voltage drop of the output cable of the power converter.

10 . The method as claimed in claim 9 , wherein the feedback signal is generated by an error amplifier; the error amplifier further comprises a reference signal for generating the feedback signal; the compensation signal is coupled to compensate the reference signal for modulating the feedback signal.

11 . The method as claimed in claim 9 , further comprising:

programming the level of the compensation signal by a resistor.

12 . The method as claimed in claim 9 , wherein the transformer signal is related to an on time of the switching signal and the level of an input voltage of the transformer.

13 . The method as claimed in claim 9 , wherein the compensation signal is generated in accordance with a demagnetizing time of the transformer.

14 . The method as claimed in claim 9 , wherein the compensation signal is generated in a secondary side of the transformer.

15 . A regulation circuit of a power converter, comprising:

a compensation circuit coupled to modulate a feedback signal in response to a transformer signal generated by a transformer of the power converter;

wherein the feedback signal is applied to generate a switching signal for switching the transformer and regulating an output of the power converter; the transformer signal is related to an on time of the switching signal and the level of an input voltage of the transformer; the feedback signal is related to an output voltage of the power converter; the output voltage is increased in response to the increase of an output current of the power converter for compensating a voltage drop of an output cable of the power converter.

16 . The regulation circuit as claimed in claim 15 , wherein the regulation circuit is located in a secondary side of the transformer.