Design rule and system parameters compare between multi-phase and multi-lamp PWM dimming control for backlight inverter

This paper proposes a novel multi-phase PWM dimming control scheme which possesses two-phase, four-phase, six-phase, and eight-phase for backlight inverter. Each phase driving circuit can control the lamp current of two ccfls at least. From the experimental results for four-phase and six-phase PWM dimming control, we got a conclusion which power efficiency η (%) is directly proportional to No. of phases and lamp current error E (%) is inversely proportional to No. of phases. Hence higher phases dimming will achieve uniform output lamp currents which is called current equalization. We develop a design rule which compare system parameters in multi-phase dimming control for backlight inverter. We conclude that the experimental results also can apply for two-phase and eight-phase PWM dimming control.