| 摘要 |
PURPOSE:To protect an integrated circuit from breakdown without its malfunctioning, by forming a region of a conductivity type identical with the conductivity type of a substrate, into a region of a conductivity type opposite to the conductivity type of the substrate and electrically connecting these two regions commonly to an terminal of an integrated circuit. CONSTITUTION:A P type region 5 composed into a N type region 2 is electrically connected to a terminal 3 as well as the N type rigion 2. In this composition, a PNP transistor is formed so that a P type substrate 1, the N type region 2, and the P type region 5 serve as an emitter, a base, and a collector, respectively. Even if a negative voltage is applied to the terminal 3 at the time of an abnormal operation, the terminal 3 is clamped on a voltage which is lowered from an earth potential by a forward rising voltage (about 0.7 V) of a PN junction, and an excessive surge voltage is absorbed, so that not only an integrated circuit connected to the terminal 3 can be protected but also the integrated circuit can be prevented from malfunctioning. |
