| 摘要 |
PURPOSE: To set an output buffer circuit at output high impedance state without fail when one of two power supplies of a semiconductor device is cut-off. CONSTITUTION: In an output circuit, a latch circuit composed of inverter circuits (2 and 22) and MOS transistors (3 and 23) is arranged in the next stage to the gate circuits (30 and 32) which accept a power supply voltage related to a 1st power supply voltage (EXVDD) as an operating power supply voltage, and a 2nd power supply voltage (VDDQ) is given as an operating power supply voltage for the latch circuit. An output buffer circuit (912) is driven according to the output of the latch circuit. Even when the 1st power supply voltage is cut off, as the operating power supply voltage signal voltage in the stand-by state is held by the latch circuit which receives the 2nd power supply voltage, so the output buffer circuit can be kept in a high impedance state without failure.
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