Quad 2-input NAND gate with open-collector outputs — what it does and where it fits
The Texas Instruments SN74S38DR is a quad 2-input NAND gate from the 74S Schottky TTL family, packaged in a 14-SOIC (0.154", 3.90 mm width) surface-mount package. Each of the four independent gates provides a NAND function with an open-collector output stage, meaning the output transistor pulls low to ground but floats high — no internal pull-up to VCC. This architecture lets you wire multiple outputs together for a wired-OR bus, drive loads at a different voltage than the logic supply, or sink significantly more current than a standard totem-pole gate. Each output sinks 60 mA when low. Propagation delay is 9 ns at 5 V with a 150 pF load. Supply voltage range is 4.75 V to 5.25 V. Operating temperature range is 0°C to 70°C.
Open-collector output — the wired-OR advantage and the pull-up resistor you must add
An external pull-up resistor is required from each output to the load supply voltage. Wired-OR connection: tie the outputs of multiple SN74S38DR gates together, and the common node goes low if any gate pulls low. This is useful for interrupt request lines, bus arbitration, or shared status flags where multiple sources need to assert a single signal. No external OR gate needed, but the pull-up resistor must be sized for the combined low-level current of all gates that could be on simultaneously.
Active production — no obsolescence concern for this BOM line
The SN74S38DR carries an active lifecycle status from Texas Instruments. For a BOM line that needs this exact quad NAND gate with open-collector outputs, there is no urgency to qualify a replacement or stockpile ahead of a discontinuation. The part is ROHS3 compliant, so it meets the current EU restriction-hazardous-substances directive without exemption. No separate lead-free qualification paperwork is needed for European or California-market shipments.