Patent ID: 7115888
Filing Date: 2006-10-03
Classification: H05B,Y02B

Abstract:
1. A light-emitting diode driving semiconductor circuit for controlling a light-emitting diode block having a choke coil to which a source voltage is applied from a voltage source, one or more light-emitting diode connected to said choke coil in series, and a diode that supplies a back electromotive force being generated in said choke coil to said light-emitting diode, the diode having one end thereof connected to said choke coil and the other end thereof connected to said light-emitting diode, said light-emitting diode driving semiconductor circuit comprising: a first input terminal connected to said light-emitting diode; a switching device block having a first FET of which one end is connected to said first input terminal or said voltage source, and a first switching device connected between said first input terminal and a ground potential; a reference voltage terminal that is connected to the other end of said first FET and outputs a reference voltage; a start/stop circuit that outputs a start signal when said reference voltage is equal to or more than a predetermined value, and outputs a stop signal when said reference voltage is less than said predetermined value; a current detection circuit that detects a current flowing from said first input terminal to said first switching device; and a control circuit that controls ON/OFF of said first switching device intermittently at a predetermined frequency based on the output signal of said start/stop circuit and the output signal of said current detection circuit so that the constant current flows through said light-emitting diode.