LED driving circuit

PROBLEM TO BE SOLVED: To provide a light-emitting diode driving circuit capable of adjusting the luminance of a light-emitting diode by switching the driving current and suppressing an increase of consumed power and a change in luminance due to the variation in characteristic of the light-emitting diode. SOLUTION: During a time period in which a switch circuit of a constant-current circuit 10 is put in an on state and a driving current IL1 is caused to flow in an LED string S1, feedback control is performed in such a manner that a voltage drop VSINK may come close to a reference voltage VP. Meanwhile, during a time period in which the switch circuit of the constant-current circuit 10 is put in an off state and the driving circuit IL1 of the LED string S1 is cut off, the feedback control is suspended. COPYRIGHT: (C)2011,JPO&INPIT