Dual 1-of-4 decoder/demultiplexer in 16-SOIC
The CD4556BM is a dual 1-of-4 decoder/demultiplexer from Texas Instruments' 4000B logic family, configured as two independent 1 x 2:4 circuits.
Operating from 3 V to 18 V, the CD4556BM covers the full 4000B supply envelope — useful in battery-backed or industrial control boards where the rail may sag or vary. Output high/low current is rated 6.8 mA each, sufficient to drive CMOS inputs on the same board or a single TTL load with pull-up.
The tube packaging suits hand-assembly or low-volume reflow; the 1.27 mm pitch is easily inspectable and reworkable with a hot-air station. No exposed pad — the thermal path is through the leads, so the ambient temperature rating assumes standard PCB copper area.