Abstract: A compensation circuit and method for constant current regulation of switching mode power supply are disclosed. The ringing waveform of a feedback signal, indicative of the output current of the power supply, causes error. To eliminate the error, a current source charges a capacitor in response to a demagnetizing oscillation signal indicative of the error caused by the ringing waveform of the feedback signal. The voltage across the capacitor is compared to a reference signal to generate a more accurate signal indicative of the conductive time of a secondary diode in a secondary winding of the switching mode power supply. This more accurate signal is inputted to a logic circuit to generate a constant current control signal to control a power switch of the power supply.

Abstract: An isolated switching mode power supply, having: a transformer having a primary winding, a secondary winding and a third winding; a current limit comparator configured to provide a current limit signal based on the current sense signal and the peak current signal; a logic circuit configured to provide a logic control signal based on the frequency control signal and the current limit signal; a startup control circuit configured to generate a startup control signal based on the current sense signal; a load detecting circuit configured to provide a load detecting signal based on the second feedback signal and the switching signal; and a selector configured to provide the logic control signal or the startup control signal based on the load detecting signal.

Abstract: An isolated switching mode power supply, having: an input terminal; an output terminal; a transformer having a primary winding and a secondary winding; a primary power switch coupled to the primary winding; a secondary power switch coupled between the secondary winding and the output terminal of the power supply; a secondary controller configured to generate a frequency modulation signal based on the output voltage and the first feedback signal; a coupled device configured to provide a frequency control signal based on the output voltage and the frequency modulation signal; and a primary controller configured to provide a switching signal to control the primary power switch based on the current sense signal and the frequency control signal.

Abstract: A switching mode power supply with improved peak current control is disclosed. A varying reference signal is adopted to limit the peak current in the energy storage component. The varying reference signal is an exponential function of a time period when a power switch is ON, wherein the power switch is coupled to the energy storage component. The varying reference signal may be generated by a circuit comprising a RC circuit and one or several voltage sources.

Abstract: A compensation circuit and method for constant current regulation of switching mode power supply are disclosed. The ringing waveform of a feedback signal, indicative of the output current of the power supply, causes error. To eliminate the error, a current source charges a capacitor in response to a demagnetizing oscillation signal indicative of the error caused by the ringing waveform of the feedback signal. The voltage across the capacitor is compared to a reference signal to generate a more accurate signal indicative of the conductive time of a secondary diode in a secondary winding of the switching mode power supply. This more accurate signal is inputted to a logic circuit to generate a constant current control signal to control a power switch of the power supply.