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Altera Corporation
APEX 20K Programmable Logic Device Family Data Sheet
Figure 8. APEX 20K LE Operating Modes
Notes:
(1)
LEs in normal mode support register packing.
(2)
There are two LAB-wide clock enables per LAB.
(3)
When using the carry-in in normal mode, the packed register feature is unavailable.
(4)
A register feedback multiplexer is available on LE1 of each LAB.
(5)
The DATA1 and DATA2 input signals can supply counter enable, up or down control, or register feedback signals for
LEs other than the second LE in an LAB.
(6)
The LAB-wide synchronous clear and LAB wide synchronous load affect all registers in an LAB.
PRN
CLRN
DQ
4-Input
LUT
Carry-In
(3)
Cascade-Out
Cascade-In
LE-Out
Normal Mode (1)
PRN
CLRN
DQ
Cascade-Out
Cascade-In
3-Input
LUT
Carry-In
3-Input
LUT
Carry-Out
Arithmetic Mode
Counter Mode
data1
(5)
data2
(5)
PRN
CLRN
DQ
Carry-In
LUT
3-Input
LUT
Carry-Out
data3 (data)
Cascade-Out
Cascade-In
LAB-Wide
Synchronous
Load
(6)
LAB-Wide
Synchronous
Clear
(6)
(4)
LE-Out
ENA
LAB-Wide
Clock Enable
(2)
ENA
LAB-Wide
Clock Enable
(2)
ENA
LAB-Wide
Clock Enable
(2)
data1
data2
data1
data2
data3
data4