LFXP3E-3QN208I Lattice, LFXP3E-3QN208I Datasheet - Page 231

• Manufacturer Part Number: LFXP3E-3QN208I
• Description: IC FPGA 3.1KLUTS 136I/O 208-PQFP
• Manufacturer: Lattice

Specifications of LFXP3E-3QN208I

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

Lattice Semiconductor
Figure 10-13. Read Data Transfer When DDRCLKPOL=1
Data Read Critical Path
Data in the second stage DDR registers can be registered either on the positive edge or on the falling edge of
FPGA clock depending on the DDRCLKPOL signal. In order to ensure that the data transferred to the FPGA core
registers is aligned to the rising edge of system CLK, this path should be constrained with a half clock transfer. This
half clock transfer can be forced in the software by assigning a multicycle constraint (multicycle of 0.5 X) on all the
data paths to the first PFU register.
Notes -
(1) DDR memory sends DQ aligned to DQS strobe.
(2) The DQS Strobe is delayed by 90 degree using the dedicated DQS logic.
(3) DQ is now center aligned to DQS Strobe.
(4) PRMBDET is the Preamble detect signal generated using the DQSBUFB primitive. This is used to
(5) The first set of IO registers A and B, capture data on the positive edge and negative edge of DQS.
(6) IO register C transfers data so that both data are now aligned to negative edge of DQS.
(7) DDCLKPOL signal generated will determine if the CLK going into the synchronization registers need to
(8) The IO Synchronization registers capture data at on negative edge of the FPGA CLK.
DDRCLKPOL=1
IO REGISTERS
CLK TO SYNC
generate the DDRCLKPOL signal.
be inverted. In this case, the DDRCLKPOL=1 as the CLK is HIGH at the 1
DQS at PIN
DQS at IOL
PRMBDET
FPGA CLK
DATAIN_P
DATAIN_N
DQ at PIN
DQ at IOL
C
A
B
P0
P0
10-12
N0
N0
P0
P1
P1
N0
P0
N1
P1
N1
P0
N0
st
LatticeECP/EC and LatticeXP
N1
P1
rising edge of PRMBDET.
DDR Usage Guide