3-15
DC and Switching Characteristics
LatticeECP/EC Family Data Sheet
Figure 3-5. DDR Timings
tDQVBS
Data Valid Before DQS
All
0.20
—
0.20
—
0.20
—
UI
tDQVAS
Data Valid After DQS
All
0.20
—
0.20
—
0.20
—
UI
fMAX_DDR
DDR Clock Frequency
All
95
200
95
166
95
133
MHz
Primary and Secondary Clock6
fMAX_PRI
2
Frequency for Primary Clock Tree
All
—
420
—
378
—
340
MHz
tW_PRI
Clock Pulse Width for Primary
Clock
All
1.19
—
1.19
—
1.19
—
ns
tSKEW_PRI
Primary Clock Skew within an I/O
Bank
All
—
250
—
300
—
350
ps
1. General timing numbers based on LVCMOS2.5V, 12 mA. Loading of 0 pF.
2. Using LVDS I/O standard.
3. DDR timing numbers based on SSTL I/O.
4. DDR specifications are characterized but not tested.
5. UI is average bit period.
6. Based on a single primary clock.
7. These timing numbers were generated using ispLEVER design tool. Exact performance may vary with design and tool version. The tool
uses internal parameters that have been characterized but are not tested on every device.
Timing v.G 0.30
LatticeECP/EC External Switching Characteristics (Continued)
Over Recommended Operating Conditions
Parameter
Description
Device
-5
-4
-3
Units
Min.
Max.
Min.
Max.
Min.
Max.
tDQVAS
tDQVBS
DQ and DQS Write Timings
t
DQS
DQ
DQS
DQ
DVEDQ
tDVADQ
DQ and DQS Read Timings