| 摘要 |
A dual mode dimming controlling device is provided to extend the voltage variable range by controlling PWM IC with burst dimming method and analog dimming method. A burst dimming part(30) produces the duty ratio control voltage determining the duty ratio of the PWM waveform. An analog dimming part(40) produces the current amount control voltage determining the current amount of the PWM waveform. A PWM IC(20) outputs FET control signal for controlling out current amount and duty ratio of PWM waveform. The PWM IC increase the duty ratio of PWM output waveform by the increase of duty ratio control voltage, and outputs FET control signal to increase PWM output waveform. |
