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DEC_CC4, 8, 16

4-, 8-, 16-Bit Active Low Decoders

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

figures/x4927n.gif

figures/x4928n.gif

figures/x4929n.gif

These decoders are used to build wide-decoder functions. They are implemented by cascading CY_MUX elements driven by lookup tables (LUTs). The C_IN pin can only be driven by a CY_INIT or by the output (O) of a previous decode stage. When one or more of the inputs (A) are Low, the output is Low. When all the inputs are High and the C_IN input is High, the output is High. You can decode patterns by adding inverters to inputs.

Inputs
Outputs
A0
A1

Az
C_IN
O
1
1
1
1
1
1
X
X
X
X
0
0
0
X
X
X
X
0
X
0
X
X
X
0
X
X
X
0
X
0
z = 3 for DEC_CC4; z = 7 for DECC_CC8; z = 15 for DECC_CC16

Figure 4.57 DEC_CC4 Implementation XC5200

Figure 4.58 DEC_CC4 Implementation Virtex

Figure 4.59 DEC_CC8 Implementation XC5200, Virtex

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