| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent an overcurrent from flowing to an LED driving circuit, especially, a constant current type LED driving circuit. <P>SOLUTION: A power supply circuit 7 includes a power supply control unit 70 which applies a voltage based upon an input control signal to an anode of an electronic member 49 in an adjustable state, and an error amplifier 73 which outputs to the power supply control unit the control signal based upon the difference between a voltage applied to an inverting input terminal and a voltage applied to a non-inverting input terminal. A cathode of the electronic member is grounded and a current detection resistor 72 is connected in series between an output terminal of the power supply unit and the anode, and one of the non-inverting and inverting input terminals of the error amplifier is connected to a high-voltage side of the current detection resistor, and a reference voltage generation unit 74 which applies a reference voltage to the other input terminal is connected between the other input terminal of the error amplifier and a low-voltage side of the current detection resistor. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
