Leadtrend Technology Corporation

National Cheng-kung University

Yi-Chuan Tsai

Ming-Chang Tsou

Tsorng-Juu Liang

Jiann-Fuh Chen

Kuan-Hsien Chou

Wei-Ching Tseng

Chang-Yi Lin

Cheng-Tsung Ho

A power factor correction (PFC) controller applied to a primary side of a power converter includes a feedback pin, a sensing pin, a current detecting circuit, an output voltage detecting circuit, and a determination circuit. The current detecting circuit is coupled to the feedback pin and the sensing pin for detecting an output current of a secondary side of the power converter according to a feedback voltage of the feedback pin and a sensing voltage of the sensing pin. The output voltage detecting circuit is coupled to the feedback pin for detecting an output voltage of the secondary side of the power converter according to the feedback voltage. The determination circuit is coupled to the current detecting circuit and the output voltage detecting circuit for turning on or turning off a PFC circuit coupled to the power converter according to the output current and the output voltage.

Power factor correction controller and operational method thereof

A controller with leakage current protection of a diode includes a comparison unit, a reference voltage generation unit, a time out signal generation unit, and a gate signal generation unit, wherein the diode is applied to a secondary side of a power converter. The comparison unit outputs a corresponding selection signal according to a compensation voltage and a threshold. The reference voltage generation unit outputs a corresponding reference voltage range according to the corresponding selection signal. The time out signal generation unit determines a corresponding time out according to the corresponding selection signal, and generates a corresponding time out signal when a voltage corresponding to an auxiliary winding has no peak to cross an upper limit of the corresponding reference voltage range during the corresponding time out. The gate signal generation unit enters the leakage current protection or a quasi-resonant mode according to the corresponding time out signal.

Controller with leakage current protection of a diode and operation method thereof

An apparatus is capable of improving the power factor of a power supply powered by a high power line and a ground power line. The apparatus comprises a line voltage detector and an ON time controller. The line voltage detector provides a scaled voltage to represent a line voltage of the high power line. The ON time controller has a valley voltage detector, which provides, in response to the scaled voltage, a valley representative representing a valley voltage of the line voltage. The ON time controller controls an ON time of a power switch in the power supply in response to the valley representative.

Power supplies and control methods capable of improving power factor during light load

An LED driver circuit includes: a bridge rectifier, a first compensation capacitor, a second compensation capacitor, and an LED module. The bridge rectifier is connected to an AC input power for producing a rectification output power. The first compensation capacitor is connected to a first rectification output terminal and an AC input terminal of the bridge rectifier. The second compensation capacitor is connected to a second rectification terminal and the AC input terminal of the bridge rectifier. The LED module is connected to the first rectification output terminal and the second rectification output terminal of the bridge rectifier. The first and second compensation capacitors in the present invention can effectively improve the total current harmonic distortion of the LED module and its utilization.

Growing community of inventors

Kaohsiung, Taiwan

Yi-Chuan Tsai