| 摘要 |
PURPOSE:To protect the circuit from the excessive input voltage without fail, without regard to the interior connecting state of the input and output terminals, by providing the current outgoing path of a protecting circuit against the excessive voltage at the input terminal on a power supply line, which is different from a grounding line. CONSTITUTION:A semiconductor integrated circuit is constituted by a power supply line 22, a grounding line 23, an MOSFET 27 which receives an input signal from a terminal 25, another MOSFET 29, and the like. An electrostatic protecting circuit PT which protects the circuit from the excessive input voltage is constituted by an MOSFET 28 and a resistor 26, and a current outgoing path is formed by connecting the input terminal 25 and the power supply line 22. If there is an excessive input, the portion between the source S and the drain D of the MOSFET 28 is conducted. Since there is a large capacity C2 between the power supply line 22 and a semiconductor substrate 20, the excessive increase in the potential of the gate G of the MOSFET 27 can be prevented. |
