| 摘要 |
PROBLEM TO BE SOLVED: To permit fine control of rotating speed, by controlling the rotating speed of a motor with an output current of a current output circuit connected to a level shifter, for outputting a pair of voltage and switching signal based on a pair of digital signals. SOLUTION: A level shifter 21 receives a pair of digital signals CON1, CON2 and outputs a voltage V and voltages of the nodes A and B. This level shifter 21 includes a first resistor R1, resistor pair R2 and R3 and transistor pair TR3 and TR4. A current output circuit 22 includes diode pair D1, D2, a resistor R8, a transistor TR6 and a transistor TR1. The digital signals CON1 and CON2 are respectively inputted to the bases of the transistors TR3 and TR4 via the inverter, thereby amplifying the amplitudes of the digital signals CON1 and CON2. Accordingly, the rotating speed of DC motor can be controlled precisely with the digital signal using the digital control circuit consisting of transistors. |
