Active 74LS multiplexer for 5V bus selection
The SN74LS257BN is an active-production 74LS-series multiplexer from Texas Instruments, configured as four independent 2:1 selector circuits in a single 16-pin DIP package.
Output drive and temperature envelope
Each output can source 2.6 mA and sink 24 mA — the asymmetric drive is typical of 74LS outputs, designed to drive one standard TTL load in the high state and up to ten loads in the low state. Housed in a 16-DIP (0.300", 7.62mm) through-hole package, the SN74LS257BN is suited for prototyping, rework, and boards where surface-mount is not an option. The 16-PDIP footprint matches standard 0.100-inch pitch DIP sockets.