The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 14, 2011
Filed:
Nov. 20, 2007
Yi-shan Chu, Hsin-Chu, TW;
Yu-bin Wang, Hsin-Chu, TW;
Hsing-kuo Chao, Hsin-Chu, TW;
Leadtrend Technology Corp., Science-Based Industrial Park, Hsin-Chu, TW;
Abstract
A pulse width modulation (PWM) control circuit is applied to a power converter with a charging capacitor. The PWM control circuit includes a PWM signal generator, a first comparator, and a reference voltage modulator. A PWM signal generator generates a PWM signal to control a power switch in the power converter. Two input terminals of the first comparator respectively receive a first reference voltage and a sensing voltage, which is proportional to a primary-side current of a transformer. When the power switch is turned on and the sensing voltage rises to the level of the first reference voltage, the first comparator outputs a first control signal to the PWM signal generator. Then, the PWM signal generator outputs a signal to turn off the power switch. The reference voltage modulator outputs the first reference voltage according to a feedback voltage relative to the output voltage of the power converter.