EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 33

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

Altera Corporation-Preliminary
March 2007
functions. When using register packing, the LAB-wide synchronous load
control signal is not available. Refer to the
for more information on the synchronous load control signal.
Another special packing mode allows the register output to feed back into
the LUT of the same LE so that the register is packed with its own fan-out
LUT, providing another mechanism for improved fitting. The LE can also
drive out registered and unregistered versions of the LUT output.
In addition to the three general routing outputs, the LEs within a LAB
have register chain outputs. Register chain outputs allow registers within
the same LAB to cascade together. The register chain output allows the
LUTs to be used for combinational functions and the registers to be used
for an unrelated shift register implementation. These resources speed up
connections between LABs while saving local interconnect resources.
Figure 2–2
shows a register cascading among LEs in Cyclone III.
Cyclone III Device Handbook, Volume 1
“LAB Control Signals”
Logic Elements
section
2–3