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X74_139

2- to 4-Line Decoder/Demultiplexer with Active-Low Outputs and Active-Low Enable

XC3000
XC4000E
XC4000X
XC5200
XC9000
Spartan
SpartanXL
Virtex
Macro
Macro
Macro
Macro
Macro
Macro
Macro
N/A

figures/x4165n.gif

X74_139 implements one half of a standard 74139 dual 2- to 4-line decoder/demultiplexer. When the active-Low enable input (G) is Low, one of the four active-Low outputs (Y3 - Y0) is selected with the 2-bit binary address on the A and B address input lines. B is the High-order address bit. The non-selected outputs are High. Also, when G is High all outputs are High.

X74_139 can be used as a 4-output active-Low demultiplexer by tying the data input to G.

Inputs
Outputs
G
B
A
Y3
Y2
Y1
Y0
0
0
0
1
1
1
0
0
0
1
1
1
0
1
0
1
0
1
0
1
1
0
1
1
0
1
1
1
1
X
X
1
1
1
1

Figure 11.5 X74_139 Implementation XC3000, XC4000, XC5200, XC9000, Spartans

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