LFXP3E-4TN144C Lattice, LFXP3E-4TN144C Datasheet - Page 343

• Manufacturer Part Number: LFXP3E-4TN144C
• Description: IC FPGA 3.1KLUTS 100I/O 144-TQFP
• Manufacturer: Lattice

Specifications of LFXP3E-4TN144C

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

HDL Synthesis Coding Guidelines
Lattice Semiconductor
for Lattice Semiconductor FPGAs
Implementation of Memories
Although an RTL description of RAM is portable and the coding is straightforward, it is not recommended because
the structure of RAM blocks in every architecture is unique. Synthesis tools are not optimized to handle RAM imple-
mentation and thus generate inefficient netlists for device fitting. For Lattice Semiconductor FPGA devices, RAM
blocks should be generated through IPexpress as shown in the following screen shot.
When implementing large memories in the design, it is recommended to construct the memory from the Enhanced
Block RAM (EBR) components found in every Lattice Semiconductor FPGA device. When implementing small
memories in the design, it is recommended to construct the memory from the resources in the PFU. The memory
utilizing resources in the PFU can also be generated by IPexpress.
Lattice Semiconductor FPGAs support many different memory types including synchronous dual-port RAM, syn-
chronous single-port RAM, synchronous FIFO and synchronous ROM. For more information on supported mem-
ory types per FPGA architecture, please consult the Lattice Semiconductor FPGA data sheets.
Preventing Logic Replication and Limited Fanout
Lattice Semiconductor FPGA device architectures are designed to handle high signal fanouts. When users make
use of clock resources, there will be no hindrance on fanout problems. However, synthesis tools tend to replicate
logic to reduce fanout during logic synthesis. For example, if the code implies Clock Enable and is synthesized with
speed constraints, the synthesis tool may replicate the Clock Enable logic. This kind of logic replication occupies
more resources in the devices and makes performance checking more difficult. It is recommended to control the
logic replication in synthesis process by using attributes for high fanout limit.
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