Dual 4:1 multiplexer in the 74ALS family
The Texas Instruments SN74ALS253N is a dual 4:1 multiplexer from the 74ALS Schottky logic family, integrating two independent 4-input multiplexers with a common select bus and individual output-enable controls. It operates from a single 4.5V to 5.5V supply and is rated for the commercial temperature range of 0°C to 70°C, making it suitable for indoor, temperature-controlled equipment such as industrial controllers, test instruments, and telecom line cards where 5V TTL/ALS logic levels are still in service.
Output drive and fan-out for the bus
The SN74ALS253N can source 2.6 mA and sink 24 mA per output, which drives up to 10 standard ALS loads on the high side and comfortably handles 20 loads on the low side. When routing a multiplexed data bus through a backplane or across a PCB, the 24 mA sink capability gives clean low-level margins even with moderate trace capacitance.
Through-hole 16-DIP for legacy and rework
Housed in a 16-pin DIP (0.300" body width, 7.62 mm pitch) with a PDIP supplier package designation, this part is through-hole mounted.