20 ns propagation delay — the speed floor for a 5 V bus
The SN74LS08DR is a quad 2-input AND gate from the 74LS family, packing four independent gates into a 14-SOIC package. Its 20 ns max propagation delay at 5 V with a 15 pF load sets the timing budget for a 5 V bus — every gate transition eats 20 ns, so a four-gate cascade adds 80 ns of combinatorial delay before the clock edge. The output stage sinks 8 mA and sources 400 µA, which is typical for the LS family — enough to drive one or two standard TTL loads but not a heavy capacitive bus. If you are fanning out to more than four inputs, buffer the output or expect the rise time to stretch past the datasheet limit.
Supply rails and input thresholds — the 5 V TTL sweet spot
The supply range is 4.75 V to 5.25 V — a tight 5 V ±5 % window. The input logic-low threshold is 0.8 V max, and the logic-high threshold is 2 V min, so it directly interfaces with 5 V TTL outputs without level shifting. A 3.3 V logic output driving a 2 V high threshold has 1.3 V of noise margin; marginal but workable if the trace is short. The operating temperature range is 0 °C to 70 °C — commercial grade. This is fine for bench equipment, office peripherals, and indoor industrial controls, but not for an engine bay or a freezer. The 14-SOIC package (3.90 mm body width) is a common footprint that routes well on two-layer boards with 0.050-inch pitch.
Active production, ROHS3 — sourcing reality
The 74LS family is widely second-sourced; if TI lead times stretch, a functionally equivalent 74LS08 from another manufacturer in the same 14-SOIC footprint is a drop-in replacement.