H.J. Chiu, T.H. Wang, and S.C. Mou (Taiwan)
LED backlight, power factor, dimming control, bypass diode
This paper presents a LED backlight driving system for large-scale of LCD panels. High efficiency, high power factor, circuit simplicity, and low cost can be achieved by using a single-stage charge-pump asymmetrical-half-bridge converter. To regulate the LED current and brightness for the LED backlight system, some current sharing methods are presented and compared. The requirements for the current sharing and luminance balance among paralleled LED arrays can be satisfied while current ripple is eliminated significantly. Because of the addition of bypass diodes, an alternative current path can be offered when a single LED fails. The LED array will not distinguish. A laboratory prototype has been built and tested. The simulation and experimental results are shown to verify the feasibility of the proposed method.
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