| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED drive circuit that can be directly driven by an AC input, and that can suppress generation of flickers, and that can achieve low power consumption.SOLUTION: An LED drive circuit for driving an LED unit having a plurality of LEDs connected in series, comprises: a rectifier for rectifying an AC input; a constant current circuit having an operational amplifier and a plurality of driving transistors connected with an output stage of the operational amplifier via a voltage dividing resistor; and resistors respectively inserted between emitters of the plurality of driving transistors and serving as voltage detectors. One end at an output side of the rectifier is connected with an input side of the LED unit, and one ends at an output side of the plurality of transistors are respectively connected with connection points of a different LED stage number in the LED unit, and thereby, the LED units of the plurality of transistors are selectively driven depending on a voltage of the AC input, and a current flowing in the selectively-driven LED unit is fluctuated depending on the voltage of the AC input. |
