What this dual 4:1 multiplexer does on a digital bus
The SN74HC253D is a dual 4:1 multiplexer from TI's 74HC family — it selects one of four data inputs per channel and routes it to a common output, controlled by a shared address bus. The two independent circuits each handle a 4:1 mux, so a single 16-SOIC package can serve two separate data paths or combine into an 8:1 mux with a chip-select.
Board-level fit and temperature range
Housed in a 16-SOIC (0.154", 3.90mm width) surface-mount package, the SN74HC253D sits on a standard SOIC footprint with 1.27mm pitch — no fine-pitch rework required. Single-supply operation simplifies the power rail: just one 2V to 6V net, no split supplies or level-shifting for the mux core. The independent circuit count of 1 means both mux channels share the same address lines but have separate output-enable controls.