A semiconductor device having an input circuit well-suited for use in a stacked-chip configuration, results in a reduction in input capacitance, and an overall improvement in transmission speed. The semiconductor device includes at least two bonding pads which receive external electrical input signals from a shared common external pin, and at least two internal circuits, each electrically coupled to a corresponding bonding pad by a signal transmission line. The semiconductor device further includes at least two protective elements, each electrically coupled to a corresponding signal transmission line, each for protecting the internal circuits from excessive electrical transmission characteristics in the input signal. At least two fuses are electrically coupled in series between the corresponding protective element and signal transmission line. The fuses are each capable of being opened to electrically insulate the protective elements from the bonding pads and the internal circuits. By keeping only one fuse active, and opening the rest, the overall system capacitance, as viewed by the common external pin, is greatly reduced.