SD686X is current mode PWM+PFM controller with built-in high-voltage MOSFET used for SMPS, with low standby power and low start current for power switch. In standby mode, the circuit enters burst mode to reduce the standby power dissipation. The switch frequency is 25~67KHz with jitter frequency for low EMI. Built-in peak current compensation circuit makes the limit peak current stable even with different input AC voltage. Limit output power can be adjusted through the resistor. Maximum peak current compensation during power-on reduces pressure on transformer to avoid saturation, the peak current compensation will decrease for balance after power-on. It integrates various protections such as undervoltage lockout, overvoltage protection, overload protection, lead edge blanking, primary winding overcurrent protection and thermal shutdown. The circuit will restart until normal if protection occurs.