CONTROL CIRCUIT FOR REDUCING CURRENT ERROR OF OUTPUT OF POWER CONVERTER AND CONTROL METHOD THEREOF

摘要

A control circuit adjusts the output of a power converter by controlling a power switch, in which a primary side of a transformer, the power switch and a sensing resistor are connected in series to ground. The control circuit includes a peak current emulating unit, an error amplifier, a comparator, and a control signal generator. The peak current emulating unit samples sampling voltages from the sensing resistor and obtains a real current sensing voltage and an current sensing voltage using the sampling voltages. The error amplifier receives a fixed reference voltage and a DC voltage generated from the output of the power converter, and generates an error signal. The comparator receives the real current sensing voltage and the error signal and generates a transition signal. The control signal generator receives the transition signal and generates a control signal for controlling the power switch.

主权项

1. A control circuit for controlling an output of a power converter by a power switch, wherein a primary side of a transformer of the power converter, the power switch and a sensing resistor are connected in this order and in series to ground, the control circuit comprising:
a peak current emulating unit for sampling a plurality of sampling voltages from the sensing resistor and then performing calculations using the sampling voltages to obtain a real current sensing voltage and an initial current sensing voltage; an error amplifier for receiving a fixed reference voltage and a DC voltage generated from the output of the power converter and generating an error signal; a comparator for receiving the real current sensing voltage and the error signal and generating a transition signal; and a control signal generator for receiving the transition signal and generating a control signal to control the power switch.