LIGHT EMITTING DIODE DRIVING DEVICE USING OPERATIONAL AMPLIFIER

摘要

PURPOSE: A light emitting diode driving device using an operational amplifier is provided to prevent unnecessary power consumption although driving light emitting diodes having different driving voltages. CONSTITUTION: An operational amplifier(OP) has the first input terminal connected to a cathode of a light emitting diode(LED), a reference voltage is applied to the second input terminal, and an output terminal connected to an anode of the light emitting diode. A resistor(R3) is connected between the cathode of the light emitting diode and a ground terminal and sets a current amount flowing into the diode. The first resistor(R1) is connected between a terminal whose voltage is higher than the reference voltage and the second input terminal, and the second resistor(R2) is connected between the second input terminal and the ground terminal. The reference voltage is set according to values of the first and second resistors.