Abstract: An apparatus for controlling an I/O interface of a chip operated in multi-power conditions includes an enable signal generator for generating an enable signal based on a chip power down signal; a reference voltage generator for generating a predetermined reference voltage in response to the enable signal; a comparator for determining a voltage required for operating the chip by comparing an external power voltage with the reference voltage in response to the enable signal; and an input/output means for performing an I/O interface function based on the voltage determined according to the comparison result of the comparator.