MAX 7000A Programmable Logic Device Data Sheet
Macrocells
MAX 7000A macrocells can be individually configured for either
sequential or combinatorial logic operation. The macrocells consist of
three functional blocks: the logic array, the product-term select matrix,
and the programmable register. Figure 2 shows a MAX 7000A macrocell.
Figure 2. MAX 7000A Macrocell
Global Global
LAB Local Array
Clear
Clocks
From
2
I/O pin
Parallel Logic
Expanders
(from other
macrocells)
Fast Input
Select
Programmable
Register
Register
Bypass
To I/O
Control
Block
PRN
D/T
Q
Clock/
Enable
Select
Product-
Term
Select
Matrix
ENA
CLRN
VCC
Clear
Select
To PIA
Shared Logic
Expanders
36 Signals
from PIA
16 Expander
Product Terms
Combinatorial logic is implemented in the logic array, which provides
five product terms per macrocell. The product-term select matrix allocates
these product terms for use as either primary logic inputs (to the ORand
XORgates) to implement combinatorial functions, or as secondary inputs
to the macrocell’s register preset, clock, and clock enable control
functions.
Two kinds of expander product terms (“expanders”) are available to
supplement macrocell logic resources:
■
■
Shareable expanders, which are inverted product terms that are fed
back into the logic array
Parallel expanders, which are product terms borrowed from adjacent
macrocells
The Altera development system automatically optimizes product-term
allocation according to the logic requirements of the design.
8
Altera Corporation
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