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In this paper, a backlight module driver driving high-power red, green, and blue light-emitting diodes (RGB LEDs) for a 19-in liquid crystal display is proposed. The DC-DC series resonant converters (SRCs) with zero-voltage switching and constant-output-current control are implemented to drive the RGB LED arrays. Phase-shifted pulsewidth modulation dimming control is adopted to effectively narrow the load variations and improve the output voltage regulations of the SRCs. A DSP-based hysteresis control algorithm is performed to track the white-color point and the specified backlight luminance. Analysis and design considerations of the proposed drivers are presented in detail. Experimental results agree well with the theoretical predictions and confirm the validity of the proposed approach.
Date of Publication: Dec. 2009