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JPE, Vol. 17, No. 2, March 2017
An E-capless AC-DC CRM Flyback LED Driver with Variable On-time Control
Kai Yao, Xiaopeng Bi, and Siwen Yang
Area Low Power Converters
Abstract LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.
Keyword CRM,Flyback converter,LED,Peak-to-average ratio
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