5 ns Schottky NOR — speed vs drive tradeoff
The SN74S02D is a quad 2-input NOR gate from the 74S Schottky family, offering 5 ns max propagation delay at 5V with a 50pF load — roughly half the delay of a standard 74LS part under the same conditions. That speed comes with asymmetric output drive: 1 mA source (logic high) versus 20 mA sink (logic low). The low-side drive handles standard TTL fan-out of 10 loads, but the high-side is limited — the gate cannot drive a heavily loaded bus line high without external pull-up or a buffer.
Supply rails and temperature grade
Runs on a single 5V rail, 4.75V to 5.25V — strict 5V ±5% tolerance, no wide-VIN margin. The 0°C to 70°C commercial temperature range suits indoor equipment, bench instrumentation, and telecom line cards in conditioned environments. Input thresholds are 0.8V low and 2.0V high, compatible with standard 5V TTL and CMOS logic families that meet the same levels. The 14-SOIC (3.90 mm width) body is a common footprint shared with 74LS and 74HC quad gates — board layout swaps without a respin.