HD74AC139

HD74AC139/HD74ACT139 Dual 1-of-4 Decoder/Demultiplexer Description The HD74AC139/HD74ACT139 is a high-speed, dual 1-of-4 decoder/demultiplexer. The device has two independent decoders, each accepting two inputs and providing four mutually-exclusive active-Low outputs. Each decoder has an active-Low Enable input which can be used as a data input for a 4-output demultiplexer. Each half of the HD74AC139/HD74ACT139 can be used as a function generator providing all four minterms of two variables. Features Multifunction Capability Two Completely Independent 1-of-4 Decoders Active Low Mutually Exclusive Outputs Outputs Source/Sink 24 mA HD74ACT139 has TTL-Compatible Inputs HD74AC139/HD74ACT139 Pin Arrangement Ea 1 A0a 2 A1a 3 O0a 4 O1a 5 O2a 6 O3a 7 GND 8 (Top view) 16 VCC 15 Eb 14 A0b 13 A1b 12 O0b 11 O1b 10 O2b 9 O3b Logic Symbol E A0 A1 E A0 A1 DECODER a DECODER b O0 O1 O2 O3 O0 O1 O2 O3 Pin Names A0, A1 E O0 to O 3 Address Inputs Enable Inputs Outputs 2 HD74AC139/HD74ACT139 Logic Diagram Ea A0a A1a Eb A0b A1b O0a O1a O2a O3a O0b O1b O2b O3b Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays. Functional Description The HD74AC139/HD74ACT139 is a high-speed dual 1-of-4 decoder/demultiplexer. The device has two independent decoders, each of which accepts two binary weighted inputs (A 0 to A1) and provides four mutually exclusive active-Low outputs ( O0 t...