CIRCUIT FOR LIGHTING VEHICULAR LIGHTING FIXTURE

摘要

PROBLEM TO BE SOLVED: To prevent a load 3 from being damaged by temporarily causing overcurrent to pass through the load 3 after inputting an electric power. SOLUTION: A circuit for lighting a vehicular lighting fixture includes: a switching regulator 1 which converts an input power into a predetermined output power and supplies it to the load 3; a current detecting component 4 for detecting current IOUTpassing through the load 3; and a feedback terminal FB, to which a voltage showing a degree of the current IOUTdetected by the current detecting component 4 is applied, and includes: a switching controller 2 which compares the voltage applied to the feedback terminal FB with a predetermined reference voltage and performs feedback control of the degree of the output power; and an overcurrent protection portion 5 which applies a voltage Vp larger than the voltage showing the degree of the current IOUTdetected by the current detecting component 4 to the feedback terminal FB only between the start of supply of an electric power to the switching regulator 1 and the switching controller 2 and the start of the switching controller 2. COPYRIGHT: (C)2011,JPO&INPIT