A technique for selecting a desired operational voltage mode in a semiconductor
memory device by applying an external command signal is disclosed. The technique
enables an internal voltage mode to be selected in response to an internal voltage
mode selection that is programmable even after the completion of the package process
for a semiconductor memory device. In one embodiment, the operational voltage mode
selection circuit of a semiconductor memory device includes a first selection signal
generating part that allows programmable selection of, or override of, a first
operational voltage mode; a second selection signal generating part that allows
programmable selection of, or override of, a second operational voltage mode; and
an operational voltage mode determining part for decoding the output of the first
and second voltage selection signal generating parts, along with programmable input
selection signals, output an operational voltage mode determining signal.
