The PWM type DC/DC converter for AC/DC provides an optimum system for all products that include an electrical outlet. It enables simpler design of a high effective converter specializing in non-isolation. By a built-in startup circuit that tolerates 650V, this IC contributes to low power consumption. A current detection resistor as internal device realizes the small power supply designs. Since a current mode control is utilized, the current can be restricted in each cycle and an excellent performance is demonstrated in the bandwidth and transient response. The switching frequency is fixed to 25kHz. A frequency hopping function is also on chip, and it contributes to low EMI. In addition, a built-in super junction MOSFET which tolerates 650V makes the design easy.