LIGHT-EMITTING DIODE DRIVE, LUMINAIRE USING THE SAME, ILLUMINATOR FOR COMPARTMENT, AND ILLUMINATOR FOR VEHICLE

摘要

PROBLEM TO BE SOLVED: To drive a light-emitting diode by a constant current regardless of whether the supply voltage of a DC power supply is higher or lower than the sum of the forward voltage of a plurality of light-emitting diodes.

SOLUTION: A light-emitting diode drive comprises a DC-DC converter 2 for stepping up or down the DC supply voltage of the DC power supply 1 to a desired DC voltage V2; a voltage detection circuit 4 for detecting the output voltage V2 of the DC-DC converter 2; a current detection circuit 5 for detecting an output current IL supplied from the DC-DC converter 2 to a luminous section 3; and a control circuit section 6 for obtaining power consumption W from a detection voltage Vx detected by the voltage detection circuit 4 and a detection current (detection voltage) Vy detected by the current detection circuit 5 and adjusting the output of the DC-DC converter 2 so that the power consumption W is within a prescribed tolerance, thus driving the luminous section 3 by a constant current regardless of whether the supply voltage of the DC power supply 1 is higher or lower than the sum of the forward voltage Vf of the plurality of light-emitting diodes LD.

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