| 摘要 |
<p>PURPOSE:To prevent the generation of malfunction at the time of connecting or disconnecting a printed circuit board in a power ON state, by using short pins for a power supply input terminal and a power supply voltage monitoring output terminal on a printed circuit board for each peripheral circuit and using long pins for other terminals. CONSTITUTION:Short pins are used for the power supply voltage monitoring output terminal 9 and the power supply input terminal 10 on the printed circuit board 6 for the peripheral circuit and long pins are used for other terminals. When the circuit board 6 is disconnected from an control printed circuit board 1 in operation, the short pins 9, 10 are disconnected at first, so that the level of a power supply voltage monitoring input terminal 2 on the circuit board 1 is turned to 'L' by a pull-down resistor 3. Thereby, the output of an OR circuit is turned to 'H' and a reset circuit 8 on the circuit board 6 is driven. When the circuit board 6 is connected to the circuit board 1 in operation, the long pin comes into contact with the circuit board 6 at first. At that time, the level of a reset input terminal 7 is 'H'. Then the short pins (terminals 10, 9) come into contact with the circuit board 1, power is supplied to the circuit board 6 and the level of the terminal 2 on the circuit board 1 is turned to 'H'. The terminal Q of a retriggerable monostable multivibrator 4 is turned to 'L' after the lapse of a prescribed time.</p> |
