Patent ID: 8305010

Claim:
A light-emitting diode lighting device comprising: a direct-current power supply; a step-down chopper including: an input terminal connected to the direct-current power supply; an output terminal connected to a load; a switching element; a first circuit that includes an impedance device and a first inductor connected in series and that is connected between the input terminal and the output terminal; and a second circuit that includes the first inductor and a diode connected in series and that is connected to the output terminal; a light-emitting diode connected, as the load, to the output terminal of the step-down chopper; a self-excited drive signal generation circuit that includes a second inductor magnetically coupled with the first inductor of the step-down chopper and that applies a voltage induced in the second inductor to a control terminal of the switching element as a drive signal to keep the switching element on; and a turn-off circuit including: a comparison device that detects a voltage of the impedance device in the step-down chopper and that outputs, when the detected voltage exceeds a reference value, an output voltage; and a switch element that is turned on by the output voltage of the comparison device such that an output terminal of the self-excited drive signal generation circuit is short-circuited and that the switching element is thus turned off.