| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a circuit device which reduces the interferential longitudinal voltage on a two-wire line, and at the same time, prevents a single-line mode from being affected adversely by emergency operations. SOLUTION: The circuit device is provided, in addition to the reducing circuit RS, with a detecting means D, which is connected to a two-wire line (A1 and A2) for transmitting differential signal and generates a stop signal when a differential signal becomes absent, and in addition, preferably, when such a high interferential longitudinal voltage that exceeds a predetermined threshold is induced, and a switch means S which stops a reducing circuit RS, when the stop signal is present. Therefore, the circuit device can reduce the longitudinal voltage across the two wires A1 and A2, when a failure occurs in a normal two-wire mode, and in addition, can prevent an effective transmission signal from being suppressed in a single-wire mode for emergency operations. The application example of the circuit device includes the CAN(controller area network) bus system of automobiles.</p> |
