| 摘要 |
[Object] To provide a LED lighting circuit for preventing an increase in an output voltage of a DC/DC converter in an unloaded state even at the time of lighting light-emitting diodes. [Means for Settlement] The LED lighting circuit includes a power factor correction circuit PFC for outputting a DC voltage V2, a DC/DC converter 1 for stepping down the DC voltage V2 and generating a DC voltage V3, an LED light source part 2 to be lit by flowing an LED current by the DC voltage V3, a control part 3 for controlling a switching element Q1 so that the LED current is constant, and a power supply part 4 for generating a DC voltage V5 for driving the control part 3, wherein the power supply part 4 and the LED light source part 2 are connected in series, the LED light source part 2 is connected to a high voltage line of the power factor correction circuit PFC, the power supply part 4 is connected to a low voltage line of the power factor correction circuit PFC, and at least at the time of lighting, the power supply part 4 is supplied with a power source from the power factor correction circuit PFC via the LED light source part 2 to generate the DC voltage V5. |
