| 摘要 |
PROBLEM TO BE SOLVED: To make the operation of an interface circuit stable. SOLUTION: A plurality of input amplifiers 20a, 20b are connected to a reception circuit 21, and they operate selectively in response to a selection signal CRS. A constant potential is applied to each input of the input amplifiers 20a, 20b respectively to prevent malfunctions. A lock detection circuit 24 outputs a lock detection signal LDS, when the operation of a demodulation circuit 23 to demodulate an output of the reception circuit 21 is synchronously with either of transmission signals DINa, DINb whichever is selected. This lock detection signal LDS is effective for only one of the input amplifiers 20a, 20b selected selected by the selection signal CRS, and the application of the constant potential to the input. |
