What this 74ALS inverting buffer does on your bus
The Texas Instruments SN74ALS540NS is an 8-bit inverting buffer with 3-state outputs from the 74ALS family. It takes eight input signals and presents their inverted logic levels at the outputs, with a 3-state enable that lets you float the outputs for shared-bus applications.
Supply rail and temperature — where it fits on the board
Package and mounting — 20-SOIC on the layout
Housed in a 20-SOIC (0.209" body width, 5.30 mm) surface-mount package, supplier device package 20-SO. No exposed pad, so thermal dissipation goes through the leads.
ROHS3 compliant, no exemption issues for EU markets.