| 摘要 |
PURPOSE:To detect a fault at a cross point without lowering the processing capability of a central controller or the like, by constituting the system so that a DC current is flowed with an analog switch closed. CONSTITUTION:When an analog switch 201 is opened, a current is flowed to a negative power source -VL through a high resistance 313, and the output of a comparator 310 is in the low level. The output of a comparator 340 in the trunk circuit side is in the low level also. When the analog switch 201 is closed, a DC current is flowed from a transistor 231 to an operational amplifier 261, and outputs of comparators 310 and 340 are changed to the high level. Consequently, output levels of comparators 310 and 340 are detected to confirm whether the analog switch 201 is opened or closed. |
