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X74_138

3- to 8-Line Decoder/Demultiplexer with Active-Low Outputs and Three Enables

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

figures/x4164n.gif

X74_138 is an expandable decoder/demultiplexer with one active-High enable input (G1), two active-Low enable inputs (G2A and G2B), and eight active-Low outputs (Y7 - Y0). When G1 is High and G2A and G2B are Low, one of the eight active-Low outputs is selected with a 3-bit binary address on address inputs A, B, and C. The non-selected outputs are High. When G1 is Low or when G2A or G2B is High, all outputs are High.

X74_138 can be used as an 8-output active-Low demultiplexer by tying the data input to one of the enable inputs.

Inputs
Outputs
C
B
A
G1
G2A
G2B
Y7
Y6
Y5
Y4
Y3
Y2
Y1
Y0
0
0
0
1
0
0
1
1
1
1
1
1
1
0
0
0
1
1
0
0
1
1
1
1
1
1
0
1
0
1
0
1
0
0
1
1
1
1
1
0
1
1
0
1
1
1
0
0
1
1
1
1
0
1
1
1
1
0
0
1
0
0
1
1
1
0
1
1
1
1
1
0
1
1
0
0
1
1
0
1
1
1
1
1
1
1
0
1
0
0
1
0
1
1
1
1
1
1
1
1
1
1
0
0
0
1
1
1
1
1
1
1
X
X
X
0
X
X
1
1
1
1
1
1
1
1
X
X
X
X
1
X
1
1
1
1
1
1
1
1
X
X
X
X
X
1
1
1
1
1
1
1
1
1

Figure 11.4 X74_138 Implementation XC3000, XC4000, XC5200, XC9000, Spartans

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