| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide: an inexpensive power supply circuit capable of detecting abnormality generated in a diode such as an LED; and a lighting system. <P>SOLUTION: An LED lighting circuit 100 includes: a constant current circuit 110 supplying current to an LED 200; a current restricting resistor 122 provided on a current path between a cathode of the LED 200 and the ground of the constant current circuit 110; and a short circuit protection circuit 120 blocking the supply of the current to the LED 200 when a potential difference between the cathode of the LED 200 and the ground of the constant current circuit 110 exceeds a predetermined voltage. Thereby, abnormality, such as a short circuit, generated in the LED 200 can be inexpensively detected without using an expensive circuit, such as an operational amplifier and a photo coupler. <P>COPYRIGHT: (C)2012,JPO&INPIT |
