National Taiwan University

Cheng-Nan Wu

Yaow-Ming Chen

A control circuit is adapted for controlling a converter. The converter includes a transformer and a power switch. The control circuit includes a current sensing unit, a current emulating unit, and a control unit. The current sensing unit senses a current flowing through the power switch coupled to a primary winding of the transformer. The current emulating unit determines a propagation delay period according to a voltage transient time of an auxiliary winding of the transformer and a turn-off time of the power switch, and retrieves several sampling times in a conduction period of the power switch according to the propagation delay period. The current emulating unit obtains a peak current and a valley current according to the sampling voltages corresponding to the sampling times. The control unit generates a control signal configured to control the power switch according to the peak current and the valley current.

Control circuit

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.

Growing community of inventors

Taipei, Taiwan

Cheng-Nan Wu