Correction Circuit of a Switching-Current Sample for Power Converters in Both CCM and DCM Operation

A method of correcting a switching-current sample for a power converter, comprising:

• generating a discharging-time signal in response to a switching signal and an input-voltage signal;
• generating a duty signal in response to said discharging-time signal, an on-time of said switching signal, and a switching period of said switching signal;
• and
• generating a corrected signal in response to an average-current signal and said duty signal;
• wherein said switching signal is utilized to switch a magnetic device for regulating an output voltage of said power converter, said discharging-time signal is correlated to a demagnetizing time of said magnetic device, said input-voltage signal is correlated to an input voltage of said magnetic device, said average-current signal is generated in response to a switching current of said power converter, and said corrected signal is coupled to generate said switching signal.

An apparatus for correcting a switching-current sample of a power converter, comprising:

• a demagnetizing-time circuit, generating a discharging-time signal in response to a switching signal and an input-voltage signal;
• a duty circuit, generating a duty signal in response to said discharging-time signal and said switching signal;
• and
• a compensation circuit, coupled to receive an average-current signal and said duty signal for generating a corrected signal;
• wherein said switching signal is utilized to switch a magnetic device of said power converter, said discharging-time signal is correlated to a demagnetizing time of said magnetic device, said input-voltage signal is obtained via a resistor coupled to an input voltage of said magnetic device, said average-current signal is generated in response to a switching current of said power converter, and said corrected signal is coupled to generate said switching signal.

An apparatus for correcting a switching-current sample of a power converter, comprising:

• a detection circuit, coupled to an auxiliary winding of a magnetic device of said power converter for generating a discharging-time signal;
• a duty circuit, generating a duty signal in response to said discharging-time signal and a switching signal;
• and
• a compensation circuit, coupled to receive an average-current signal and said duty signal for generating a corrected signal;
• wherein said switching signal is utilized to switch said magnetic device, said discharging-time signal is correlated to a demagnetizing time of said magnetic device, said average-current signal is generated in response to a switching current of said power converter, and said corrected signal is coupled to generate said switching signal.