What this 4000B decoder/demux does on the board
The Texas Instruments CD4556BM96 is a dual 1-of-4 decoder/demultiplexer from the 4000B logic family. It takes a 2-bit binary address input and activates one of four active-low outputs on each of the two independent decoder sections. This part is the go-to for address decoding in memory-mapped I/O, routing control signals in industrial PLC backplanes, or fanning out a single data stream to multiple channels in instrumentation front-ends. The wide 3V to 18V supply range means it can sit on a 5V or 12V rail without a level translator, and the -55°C to 125°C temperature grade qualifies it for avionics, downhole tools, and outdoor telecom cabinets where the ambient swings hard.
Two decoders in one 16-SOIC — what that saves you
Two independent 1:4 decoder circuits in a single 16-SOIC package. Each decoder section drives 6.8 mA source or sink at the outputs.
Sourcing and lifecycle — still a current-production part
The CD4556BM96 carries an Active product status with ROHS3 compliance. For a BOM line that needs a 4000B decoder in SOIC, this is a low-risk, production-ready choice. The 'M96' suffix indicates the 16-SOIC tape-and-reel variant; the same die is also available in other packages if your assembly line prefers tubes or trays.