Control circuit of light-emitting element

Abstract

A control circuit of a light-emitting element comprises a rectifying unit (30) which full-wave rectifies an alternating current power supply, a switching element (38), a reference voltage generating unit (40) which generates a reference voltage (Vref), and a comparator (42) which receives a voltage (Srec) rectified by the rectifying unit (30), compares a comparative voltage (Vcmp) corresponding to a current flowing to an LED (102) and the reference voltage (Vref), and controls switching of the switching element (38) according to a comparison result, wherein the reference voltage generating unit (40) comprises a voltage dividing circuit having a transistor (Q1) in which a resistance value between a source and a drain is changed according to the voltage rectified by the rectifying unit (30), and outputs, using the voltage dividing circuit, the reference voltage (Vref) according to the voltage (Srec) rectified by the rectifying unit (30).

Dependencies are inferred from the claim text.