74S NAND gate in a 14-SOIC footprint
The SN74S140NS is a dual 4-input NAND gate from TI's 74S Schottky logic family, packaged in a 14-SOIC (0.209", 5.30 mm width) surface-mount body with the 14-SO supplier device package marking. The 74S series uses Schottky-clamped transistors to reduce storage time, so propagation delay sits at 6 ns typical at 5 V with a 150 pF load — fast enough to handle 20-30 MHz clock distribution or address decoding in a 5 V-only system without needing a separate high-speed logic family.
Input logic-low threshold is 0.5 V max; logic-high is 3.4 V min. That 3.4 V high threshold is higher than a 3.3 V CMOS output can guarantee — this gate expects 5 V TTL levels on its inputs, so a 3.3 V microcontroller needs a level translator or an open-drain buffer pulled up to 5 V before driving the SN74S140NS. Output current capability is 40 mA sourcing (logic high) and 60 mA sinking (logic low).
Temperature grade and operating envelope
Fine for benchtop instrumentation, telecom racks with active cooling, or factory-floor cabinets that stay above freezing. Not rated for the -40°C cold start of an automotive or outdoor enclosure.