| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED lighting device in which such problems as increase in stress of circuit components or noise generation can be prevented even if one or a plurality of LED units are connected, and to provide a lighting fixture and an illumination system using the same.SOLUTION: An LED lighting device includes a step-down converter circuit 4 having three output connectors 41 connected in series, and supplying an LED current I1 to an LED unit 7 or a dummy unit 72 connected with each output connector 41, a step-down converter control circuit 5 for controlling the output from the step-down converter circuit 4, and a number determination circuit 6 for determining the connection number of LED units 7. The number determination circuit 6 determines the connection number of LED units 7 based on the resistance across a series circuit 42 consisting of three output connectors 41, and the step-down converter control circuit 5 controls the output from the step-down converter circuit 4 depending on the connection number of LED units 7. |
