The FAN7685/FAN7686/FAN7687 is a complete output supervisory circuitry intended for use in the secondary side of the switched mode power supply. It provides overvoltage protection (OVP), undervoltage protection(UVP), overcurrent protection (OCP), and power good signal generator to monitor and control the outputs of the switching power supply system. Remote on/off(PSON) control and some precision protection features are also implemented. It directly senses all the output rails for OVP, UVP, and OCP without external divider resistors. As for output control, power good output(PGO) and fault protection output(FPO) are included. The FAN7685/FAN7686/FAN7687 offers a simple and cost effective solution with minimum number of external components and greatly reduces PCB board space for power supply.