| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an inexpensive cable connection detecting circuit requiring only one wire for detecting whether a cable is connected or not, and capable of reducing a substrate area. <P>SOLUTION: The cable connection detecting circuit 10 detects a connection/no connection of a cable 40 to be connected between an output terminal 21 of a first device 20 provided with a driver circuit 22, a DC cutting capacitor C1 connected to an output side of the driver circuit 22, and a matching resistance Ra connected between the capacitor C1 and the output terminal 21; and an input terminal 31 of a second device 30 provided with a matching resistance Rb connected between the input terminal 31 and grounding GND. The cable connection detecting circuit 10 includes a voltage detecting circuit 12 detecting a voltage of a common connection point A of the capacitor C1 of the first device 20 and the matching resistance Ra; and a comparator for output of a signal which indicates that the cable 40 is not connected when a voltage V<SB>B</SB>to be detected by the voltage detecting circuit 12 exceeds a preset threshold voltage Vth, and that the cable 40 is connected when the voltage V<SB>B</SB>is less than the threshold voltage Vth. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
