| 摘要 |
PROBLEM TO BE SOLVED: To provide a signal voltage regulating system in which an input voltage does not become an overvoltage even when the power source voltage and the ground voltage of a semiconductor integrated circuit device are shifted. SOLUTION: The signal voltage regulating system includes an input voltage regulating means 14 for regulating the "H" level of an input signal to the semiconductor integrated circuit device 11 to a predetermined value which does not exceed the power source voltage Vdd1, with the power source voltage Vdd1 of the power source terminal 17 of the semiconductor integrated circuit device 11 and the ground voltage VGnd1 of a ground terminal 18 as reference voltages, and regulating an "L" level to a predetermined value which does not lower from the ground voltage VGnd1; and inputs the input signal regulated to the predetermined value by the input voltage regulating means 14 to the semiconductor integrated circuit device 11. The input voltage regulating means 14 has a resistor 25 and an n-MOSFET 26 connected in series, and an inverter 27 connected between the connecting point of the resistor 25 and an n-MOSFET 26 and an input terminal 19 of the semiconductor integrated circuit device 11. COPYRIGHT: (C)2005,JPO&NCIPI
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