Abstract: A winding structure of an inductor used in a power factor correction circuit is provided. The winding structure includes a ring-shaped core with a gap, a first coil and a second coil wound around the core. The negative end of the first coil and the positive end of the second coil is coupled to form a central tap.

Abstract: A pulse width modulation integrated circuit (PWM IC) chip available as an 8-pin DIP or a 14-pin SOP package is characterized by simplified circuit complexity, high package density, more voltage regulation functions and more pin functions. The PWM IC of the present invention uses several internal control circuit to create and define the pin functions thereof and is capable of controlling the switch of the internal power control circuit therein, modulating the operation frequency of the PWM IC, accomplishing the voltage feedback operation of the power supply, sensing the external current and increasing the pulse width of the output pulse signal tardily as the PWM IC starts up. More specifically, because the PWM IC of the present invention employs internal current sources to create and define the pin functions thereof, the PWM IC can be equipped with less pin numbers, simpler circuit complexity and higher package density.

Abstract: A winding structure of an inductor used in a power factor correction circuit is provided. The winding structure includes a ring-shaped core with a gap, a first coil and a second coil wound around the core. The negative end of the first coil and the positive end of the second coil is coupled to form a central tap.