Dual 1-of-4 decoder for address decoding and signal routing
The CD4555BMT: The Texas Instruments CD455BMT is a dual 1-of-4 decoder/demultiplexer from the 4000B series. Each of the two independent circuits takes a 2-bit binary address input and asserts one of four active-high outputs.
The 3V to 18V supply range is the 4000B series' defining advantage over 74HC or 74LS families: it lets the same part bridge a 3.3V microcontroller to a 12V relay driver or run directly from a 9V battery. The dual supply source tag means the part can be used with separate VDD and VSS rails, though in practice most designs tie VSS to ground and run single-supply.
Package and footprint: 16-SOIC surface-mount
The narrow SOIC body saves board area compared to the wider SOIC-16 (7.5mm) variant.
Lifecycle and sourcing posture
Listed as Active on TI's product status, with ROHS3 compliance. For dual-sourcing resilience, note that the 4000B series is second-sourced by multiple manufacturers (e.g., ON Semiconductor MC14555B), though the exact pin-compatible alternate is not in this ledger.