A cold cathode fluorescent lamp driving circuit without a transformer for liquid crystal display backlight unit

Abstract

A cold cathode fluorescent lamp driving circuit without a transformer for liquid crystal display backlight unit is proposed. Commonly, a CCFL driver has a transformer with high turn ratio to step up low input voltage to high sinusoidal lamp voltage. This high voltage and high turn ratio transformer has large size and high cost. The proposed CCFL driving circuit which is based on parallel-loaded resonant topology features simplicity, so it reduces complexity and cost of overall system. And the proposed circuit with asymmetric control has dimming capability by duty control. In this paper, the analyses of the proposed CCFL driving circuit and experimental results for BLU of 32-inch commercial LCD TV are presented.