What this triple NOR gate brings to a 5V logic rail
The SN74AS27N packs three independent 3-input NOR gates into a single 14-pin DIP, each gate swinging between 4.5V and 5.5V with a propagation delay of 5.5ns into a 50pF load at 5V — fast enough to keep up with most asynchronous glue logic in a 5V TTL system.
Logic thresholds and output drive
Input low threshold is 0.8V max, high threshold 2V min — standard TTL-compatible levels that let it interface directly with 74LS, 74S, and 74F families without level translation. Output drive is rated 2mA source and 20mA sink — the asymmetric drive is typical of AS logic, meaning the gate can sink a fan-out of 10 standard LS loads but sources only one. That matters when driving a bus line or LED: the low-side pull is strong, the high-side is weak.
Housed in a 14-pin PDIP (0.300" body width), the SN74AS27N is a through-hole part that fits standard breadboards and 0.100" pitch prototyping grids — no fine-pitch soldering needed.