LED driving semiconductor circuit and LED driving apparatus including the same

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.