5V TTL octal bus transceiver — the 74LS workhorse
The Texas Instruments SN74LS245NS is an octal (8-bit) bidirectional bus transceiver from the 74LS Schottky TTL family. It provides non-inverting data flow between two 8-bit buses, controlled by a direction pin (DIR) and an output-enable pin (OE) that puts the outputs into a high-impedance 3-state condition. The part operates from a 4.75V to 5.25V supply and delivers 15mA sink / 24mA source drive at the outputs — typical for the 74LS logic level. This is the surface-mount variant in a 20-SOIC (0.209-inch wide, 5.30mm body width) package, designated 20-SO.
Supply rail and temperature grade — design-in constraints
The 4.75V–5.25V supply range means this part is strictly a 5V TTL device. It cannot be run from 3.3V or lower rails.
Package and footprint — 20-SOIC surface mount
The 20-SOIC package (0.209-inch body width, 5.30mm) is a standard surface-mount footprint shared with many 74LS and 74HC octal transceivers. This is a tube-shipped part, not tape-and-reel, which may affect pick-and-place handling for high-volume assembly lines.