| 摘要 |
PURPOSE:To suppress the current capacity of a power circuit low even when many circuits are provided, by connecting the middle point of the series circuit of a capacitor and a resistance, connected between a positive and a negative power terminal, to the LED of a photocoupler. CONSTITUTION:To one input terminal 2 of an NAND circuit 1, input data 3 is applied and to the other input terminal 4, a data readout signal 5 having much shorter pulse width than that of the input data 3 is applied. Further, the series circuit 10 of a capacitor 8 and a resistance 9 is connected between positive and negative power terminals 6 and 7, and the middle point 11 of the series circuit 10 and the output terminal 12 of the NAND circuit 1 are coupled mutually by the series circuit 16 of the LED14 of a photocoupler 13 and a current-limiting resistance 15. When the output of the NAND circuit 1 is at a level L, the charge of the capacitor 8 is discharged through the LED14 and light emitted by the LED14 at this time is photodetected by a phototransistor 17, thereby obtaining output data 19 from the middle point of the series circuit including a load resistance 18. |
