| 摘要 |
<p>PURPOSE:To prevent the generation of device destruction due to a leakage current or malfunction due to reset. CONSTITUTION:A current/voltage converter 24 connected to a signal line between an I/O connector 11 and an analog switch 15 through diodes 22, 23 converts a leakage current flowing from the signal line when a power supply for an I/O device 14 is OFF and a power supply for a peripheral apparatus 60 is ON into about 2 to 3V voltage. The switch 15 is driven by the voltage as operation power supply so as to be closed when a power supply line 13 is OFF and opened when the line 13 is ON. Thereby the inflow of a leakage current from the peripheral apparatus 60 to the I/O device 14 can be suppressed. When the line 13 is OFF, the output of a voltage/signal converter 33 is turned to 'L' and the output voltage of a voltage/signal converter 25 is turned to he 'H' level. Thereby when the line 13 is OFF, the output of an AND gate 31 is turned to the 'H' level and a transistor 32 is turned on, so that the charged electricity of a capacitor 17 is discharged.</p> |
