The SN74HCT157DR is a 4-channel 2:1 multiplexer from the 74HCT logic family, operating from a single 4.5V to 5.5V supply. Each of the four sections selects one of two data inputs and routes it to the output, controlled by a common select line. Output drive capability is rated at 6 mA source and 6 mA sink per channel — sufficient for driving standard TTL loads or the input of a downstream CMOS gate without an external buffer.
The 16-SOIC footprint is widely used and compatible with automated pick-and-place assembly. The single-supply 5V rail simplifies power distribution — no negative rail or split supply needed. Decouple with a 0.1 µF ceramic capacitor placed within 5 mm of the VCC pin to keep switching noise below the logic threshold.