The S6520 contains all of the necessary control circuitry to implement a highly efficient cold cathode fluorescent back-light driver and provides a near sinusoidal output voltage and current waveforms for a CCFL. A specially designed integrated circuit provides all control functions for a current fed push-pull converter and contains two PWM(Pulse Width Modulation) control circuits to drive 4 CCFLs for LCD monitor. The S6520 operates at constant frequency in a PWM mode and it has feed forward control method, this function preventing lamp flickering against input voltage step changing. Therefore, even though input voltage is changed suddenly, the lamp current remains constant because of the feed back and feed forward control. Typical operating frequency ranges between 30kHz to 200kHz, dependent upon the CCFL and transformer characteristics. It provides protection functions such as OLP(Open Lamp Protection), SCP(Short Circuit Protection).