| 摘要 |
PURPOSE:To prevent a driver from malfunctioning and to perform stable driving operation by providing a power-source temporary turning-off circuit which cuts off power supply to a pull-up resistor when a power-on or reset command to a microcomputer is generated. CONSTITUTION:The power-source temporary turning-off circuit 15 is provided between the pull-up resistor 7 and a terminal RESET/IN of the microcomputer MC and consists of a C-MOS12 as an inverter, a switching transistor (TR)13, and a resistor 14. When a reset signal is sent out in power-on operation or when a manual switch 4 is pressed, the input to the C-MOS12 falls to LOW for a specific time and the reset signal is sent from the MC to ICs 2 and 3, so that ports PA0,... of the ICs 2 and 3 enter a floating state. The TR13, on the other hand, turns off and a load 8, e.g. clutch A is not driven. The input to the C-MOS12 goes up to HIGH a specific time later and the TR13 turns on to supply electric power to the resistor 7. Thus, the driver is prevented from malfunctioning.
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