| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital input circuit capable of increasing the response speed, at a low cost. SOLUTION: The digital input circuit includes a pair of input terminals T3, T4 for inputting input signal; and a general-purpose photocoupler PC5 which transmits input signal from the pair of input terminals T3, T4 to an input port T1 side of a microcomputer 12. A light-emitting diode LD6 of the photocoupler PC5 is connected to, between the pair of input terminals T3, T4, a collector terminal of a photo transistor PT8 is connected to the plus side of a power source VCC, and the emitter terminal of the phototransistor PT8 is grounded to the ground via a resistor R14. A transistor TR13 is provided between a pull-up resistor R22, which pulls up an input port T1 of the microcomputer 12 and the ground, the transistor having a collector terminal connected to the pull-up resistance side, an emitter terminal connected to the ground side, and a base terminal connected to a connecting point A, between the emitter terminal of the phototransistor PT8 and the resistor R14. COPYRIGHT: (C)2011,JPO&INPIT
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