PWM SIGNAL GENERATING CIRCUIT FOR DC-DC CONVERTER USING DIMING SIGNAL AND LED DRIVER CIRCUIT HAVING THE SAME IN FIXED PHASE DIGITAL DIMMING METHOD

摘要

PURPOSE: A PWM signal generation circuit for a DC-DC converter and an LED driving circuit using the same are provided to reduce ripple of output voltage by creating a dimming signal synchronized in an internal clock. CONSTITUTION: A dimming signal generating unit(100) creates a dimming signal according to a control signal for driving an LED. An oscillator creates a first clock signal having established frequency. A synchronization block(200) synchronizes the created dimming signal in the first clock signal. A PWM(Pulse Width Modulation) signal generator(300) creates a PWM signal by using the synchronized dimming signal. A DC-DC converter(400) provides output voltage to an LED array(600) by using the PWM signal. An LED driving unit(500) drives the LED array by using the dimming signal.