SEMICONDUCTOR APPARATUS

PROBLEM TO BE SOLVED: To prevent remarkable reduction of operation speed of an interface circuit even when external power source voltage is reduced to be used, in a semiconductor apparatus having an internal power source. SOLUTION: The semiconductor apparatus is provided with a voltage converting circuit 14 converting a first internal signal of an internal power source voltage system transferred from an internal circuit to a second internal signal of an external power voltage system, a voltage comparison discriminating circuit 15 discriminating magnitude relation of potential difference between the external power source voltage and the internal power source voltage and the prescribed reference value, a switching circuit 16 to which the first internal signal and the second internal signal are input, in which switching control is performed by a voltage comparison discrimination output signal, and which selects any signal and outputs it, an output control circuit 17 receiving the first internal signal transferred from the internal circuit and a signal guided from the switching circuit and generating a drive control signal, and an output buffer circuit 18 having a MOS transistor of a current output side and a MOS transistor of a current absorbing side in which on/off operation is controlled by a logic level of the drive control signal. COPYRIGHT: (C)2007,JPO&INPIT