Circuit for decreasing current consumption in data output circuit in case one of two supply voltages fails

摘要

An improved output buffer circuit applicable to dynamic random access memories (DRAms) is disclosed. First power supply voltage Vcc1 is supplied to a conventional output main amplifier 3ai. Second power supply voltage Vcc2 is supplied to output driver circuit 4i. Potential fixing circuit 3bi operated in response to power supply failure detecting signal PFR of first power supply voltage Vcc1 is connected to the output of output main amplifier circuit 3ai. When second power supply voltage Vcc2 is applied without first power supply voltage Vcc1 being supplied, the gates of driving transistors Q1 and Q2 are fixed to ground potential in response to the signal PFR. Consequently, undesired current consumption is avoided, since a penetrating current does not flow through transistors Q1 and Q2.