The CS51221 fixed frequency feed forward voltage mode PWM controller contains all of the features necessary for basic voltage mode operation. This PWM controller has been optimized for high frequency primary side control operation. In addition, this device includes such features as: Soft-Start, accurate duty cycle limit control, less than 50mA startup current, over and undervoltage protection, and bidirectional synchronization. The CS51221 is available in a 16 lead SOIC narrow surface mount package.