Patent ID: 8593067

Claim:
An LED lighting device comprising: a DC source; a non-insulated step-down chopper including: a first circuit in which a switching element, a current detecting impedance element and an inductor are connected in series to each other through which an increased current flows when the switching element is turned on; a second circuit in which the inductor and a freewheel diode are connected in series to each other through which a decreased current flows when the switching element is turned off; a control portion for controlling at least the switching element, wherein the current detecting impedance element is connected between a cathode of the freewheel diode and a source of the switching element, the control portion turns off the switching element when the increased current flowing in the current detecting impedance element reaches a first predetermined value, and the control portion turns on the switching element when the decreased current flowing in the inductor reaches a second predetermined value smaller than the first predetermined value, wherein the control portion and the switching element are constituted by a single package IC, a control power of the IC is supplied from a secondary winding which is magnetically coupled to the inductor, and at least the current detecting impedance element and the inductor are attached to the outside of the IC; and a light emitting diode connected to a position on a circuit through which the increased current and the decreased current of the non-insulated step-down chopper flow.