| 摘要 |
PURPOSE:To prevent a current from flowing between a first potential point and a second potential point no matter what the relation between the potential levels of the first and second potential points may be by a method wherein two-P-MOS transistors are connected in series on a P-type semiconductor substrate and a diode is inserted in the second potential point on a high-potential side. CONSTITUTION:A first P-channel MOS transistor 4, which is formed on a first N-type well layer 11 formed on a P-type semiconductor substrate 10 and whose source 12 is connected to a first potential point 1, and a second P-channel MOS transistor 3 formed on the above N-type well layer 11 in the same way as the above transistor are provided and an output terminal 7 that makes respective drains 13 of the first and second P-channel MOS transistors 4 and 3 common is provided. Moreover, a diode 17, which is formed adjacent to the above first N-type well layer 11 and whose cathode 19 and anode 20 are respectively connected to the source 14 of th second P-channel MOS transistor 3 and to a second potential point 2, is provided on the above P-type semiconductor substrate 10. |
