US Patent No. 10,193,456

PULSE WIDTH MODULATION CONTROLLER AND RELEVANT CONTROL METHOD HAVING MINIMUM ON TIME IN RESPONSE TO VOLTAGE PEAK OF LINE VOLTAGE


Patent No. 10,193,456
Issue Date January 29, 2019
Title Pulse Width Modulation Controller And Relevant Control Method Having Minimum On Time In Response To Voltage Peak Of Line Voltage
Inventorship Wei Cheng Su, Zhubei (TW)
Chi Pin Chen, Zhubei (TW)
Assignee LEADTREND TECHNOLOGY CORPORATION, Zhubei, Hsinchu County (TW)

Claim of US Patent No. 10,193,456

1. A PWM controller for providing to a power switch a PWM signal determining an ON time and an OFF time of the power switch, the PWM controller comprising:a peak detector for detecting a voltage peak of a line voltage generated by rectifying an alternating-current input voltage;
an OFF-time control unit for controlling the PWM signal and determining the OFF time in response to a compensation voltage, wherein the compensation voltage is in response to an output voltage of a power supply comprising the power switch and the PWM controller; and
an ON-time control unit for controlling the PWM signal and determining the ON time in response to the compensation voltage and the voltage peak, wherein the ON-time control unit is configured to make the ON time not less than a minimum ON time, and the minimum ON time is determined in response to the voltage peak;
wherein the ON-time control unit comprises a ramp signal generator for providing a ramp signal compared with the compensation voltage to determine the ON time; and
the ramp signal generator provides a charging current in response to the voltage peak to charge a capacitor and generate the ramp signal.