Effects of a Current Field on the Characteristics of Irregular Waves

A power factor correction circuit includes a boost converter, a zero-current detector for detecting a period in which an inductor current is zero, a half-wave rectifier for supplying a power voltage proportional to an output voltage of the boost converter, a control voltage generator for generating a control voltage to control the turn-on time timing of a sense-FET, a turn-on controller for making constant a turn-on duration of the sense-FET, an over current detector for generating a signal when a mirror terminal current of the sense-FET is greater than a predetermined current, an OR gate for performing a logic OR operation of the output signals of the turn-on controller and the over current detector, an output current controller for generating a gate drive signal of the sense-FET, and an under voltage lock out for turning off the power voltage when the power voltage is less than a predetermined voltage. This circuit enables an external pin count to be reduced by having a built-in boost converter controller and a built-in sense-FET in a single package.