| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an LED drive circuit capable of fully turning off LEDs at a low cost. <P>SOLUTION: Since transistors 14c and 14d functioning as differential input transistors in an unbalanced differential amplifier circuit 14a of a buffer circuit 14 are PNP transistors, the buffer circuit 14 is an ejection type of an input signal, and a current does not flow into a base of the transistor 14c from a node α, which is located at a cathode side of an LED series circuit 11. Moreover, since the buffer circuit 14 has a discrete configuration, the buffer circuit 14 can be achieved with a simple configuration at a low cost even if the number of LEDs 12 connected in series to one another constituting the LED series circuit 11 becomes large and a DC voltage Vcc applied to the LED series circuit 11 becomes high, thereby providing an LED drive circuit 10 at a low cost. <P>COPYRIGHT: (C)2013,JPO&INPIT |
