| 摘要 |
PURPOSE:To prevent the attenuation of a signal occurring when a voltage exceeding a power supply voltage is inputted to an input terminal as a signal in a P-channel MOS transistor of a static electricity breakdown protection circuit. CONSTITUTION:In a P-channel MOS transistor 13 of a static electricity breakdown protection circuit. a gate G and an N well W are connected and the gate G and N well W are kept floated. When a voltage Vin exceeding the power supply voltage is applied to an input terminal 11 as a signal, the potential of the N well W becomes equal to that of the gate G. At this time, no current leaks to the N well W from the input terminal. Also, at this time, the P-channel transistor 13 does not operate. Therefore, even if a voltage exceeding the power supply voltage is inputted as a signal, the signal is not attenuated by the static electricity breakdown protection circuit and is transferred to an internal circuit. |
