What the S-Series 2-Line MUX TTL Means for Your BOM
The SN74S158N is a 2-line input multiplexer from Texas Instruments' S Series TTL logic family. It selects one of two data inputs and routes it to the output, controlled by a common select line — a standard building block for data routing, bus isolation, or register-file addressing in legacy TTL-based systems. Because it is S-Series TTL (Schottky-clamped), it offers faster propagation delays than standard 74-series parts, typically in the 5-8 ns range, making it suitable for higher-speed logic paths in existing designs that cannot migrate to a newer logic family without a board spin.
Lifecycle and Compliance — Active but RoHS Non-Compliant
The part is RoHS non-compliant. This means it contains lead (Pb) in the solder finish or internal construction and cannot be used in products sold into RoHS-regulated markets unless a specific exemption applies. For legacy BOMs that already accept tin-lead solder, this is not a blocker — but any new design-in should verify the exemption or plan for a RoHS-compliant alternative.
Package and Handling — Bulk Tube, Not Reel-Ready
The SN74S158N ships in Bulk packaging — loose tubes, not tape-and-reel. For a pick-and-place line, this means the parts must be hand-loaded into a tube feeder or bulk tray; the line does not auto-feed from a reel. Plan for manual handling at the placement station. The DIP package (N suffix) is through-hole, so it survives reflow without MSL concerns — no bake required before soldering. The lead pitch is 2.54 mm (0.1 inch), standard for DIP sockets or wave-solder through-hole pads.