Dual 1:4 decoder in a 16-TSSOP footprint
The SN74HC139PWR is a dual 2-line to 4-line decoder/demultiplexer from Texas Instruments' 74HC family. Each of the two independent circuits takes a 1-bit address input and enables one of four active-low outputs, making it a compact address decoder for memory-mapped peripherals or a demultiplexer for routing a data signal to one of four channels. Housed in a 16-TSSOP package (4.40 mm wide, 0.65 mm pitch), it fits high-density boards where board area is tight.
Operating from 2 V to 6 V, the 74HC logic family delivers consistent propagation delays across the supply range — at 4.5 V typical tpd is around 15 ns, though the exact figure depends on load capacitance. Each output can source or sink 5.2 mA at the rated supply — enough to drive a standard CMOS input or a low-power LED indicator directly, but not a relay coil or bus line without a buffer.