SD4870 is a current mode PWM controller IC for high performance, low standby power offline flyback converter application. In no load or light load condition, the IC operates in Light Load Mode to reduce switching loss and improve efficiency. Large value startup resistor could be used in the startup circuit to minimize the standby current because of low startup current. SD4870 offers complete protection functions including cycle-bycycle over current protection, over load protection, VDD input voltage over voltage and under voltage protection, etc. Excellent EMI performance is achieved with frequency shuffling technique and soft switching control at the totem pole gate driver output.