8-bit parallel-load shift register — what the function means for the BOM
The SN74166N3 is an 8-bit parallel-in, serial-out shift register from Texas Instruments' 74-series TTL logic family. It loads eight parallel data bits on a single clock edge and shifts them out serially on the next eight clock cycles — a standard building block for expanding microcontroller inputs, scanning switch matrices, or capturing parallel data over a single-wire serial link. The '166 function is the same as the classic 74166, but the 'N3 suffix indicates a specific package and lead-finish variant that is RoHS non-compliant, so it belongs on BOMs that either require legacy tin-lead plating or carry an explicit RoHS exemption for leaded solder.
The RoHS non-compliant flag is the main planning constraint — if your assembly line has moved entirely to lead-free reflow, this part requires either a segregated wave-solder step or a qualified exemption.
Package and mounting — through-hole DIP, Bulk shipment
the SN74166N3 comes in a standard DIP body — the same 16-pin 0.3-inch-wide footprint used by the 74166 and most 74-series 16-pin logic. No moisture-sensitivity bake is required for a hermetic DIP, but standard ESD handling applies.