The NXP PCA9543AD,118 is a 2-channel I²C multiplexer designed to route I²C or SMBus traffic between a single upstream bus and two downstream channels. It lives in a 14-SOIC package (0.154" body width, 3.90 mm) and operates from a 2.3 V to 5.5 V supply, which means it drops into both 3.3 V and 5 V logic systems without a level translator.
If you're running a 3.3 V bus, the PCA9543AD works without extra pull-up adjustments. At 5 V, it handles legacy 5 V-only peripherals. The I²C and SMBus interface support means it can be used with standard I²C controllers or SMBus hosts — just check the bus capacitance and pull-up resistor sizing for your channel count.
The 14-SOIC package is a surface-mount footprint that's easy to hand-solder or reflow. The 0.154" body width is the narrow SOIC variant, so verify your PCB land pattern matches the 3.90 mm width.
It's ROHS3 compliant. For production quantities, the Tape & Reel option is the usual choice; for evaluation or repair, Cut Tape works.