Browsing by Author "Tai, Ting-Jung"

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SAR-Controlled Adaptive Off-Time Technique Without Sensing Resistor for Achieving High Efficiency and Accuracy LED Lighting System
(2010-06-01)
Liu, Chao-Hsuan
;
Hsieh, Chun-Yu
;
Hsieh, Yu-Chiao
;
Tai, Ting-Jung
;
Chen, Ke-Horng
A successive approximation register (SAR) is utilized to control adaptive off-time in order to regulate accurate light-emitting diode (LED) current and improve efficiency of LED driver. The proposed SAR-controlled adaptive off-time technique without the external sensing resistor can sense the current flowing through LEDs during the turning on of the N-type power MOSFET, as well as provide adaptive off-time depending on the input voltage and the numbers of LED, to obtain an accurate LED current. Experimental results show the inductor current ripple is kept within +/- 15% of the DC current. As a result, line regulation is guaranteed in this proposed design.