SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

摘要

PURPOSE:To prevent application of input voltage to its input/output circuit which exceeds its power source voltage in an integrated circuit device which uses different power source voltages. CONSTITUTION:A voltage changeover circuit, which is operated by a signal to be supplied to a buffer, is interposed between an output buffer 2 and a pad 1. When higher voltage exceeding a power source voltage is applied from outside, the board potential is adapted to be identical to the outside voltage or exceed the voltage. This construction makes it possible to reduce the voltage applied from the outside so that it may be smaller than the power source voltage of the buffer before the application to the output buffer.