There are two constraints requirements for each signal group in the RLDRAM 3 memory interface:
•Maximum delay constraints
•Skew constraints
The maximum delay constraints are shown in Table: RLDRAM 3 Memory Maximum Delay Constraints.
Signal Group |
Reference Figure |
Maximum Delay Constraints (ps) |
---|---|---|
address/command |
1017 |
|
Data signals P0+L0+L1+L2 |
1017 |
The skew constraints are listed in Table: RLDRAM 3 Memory Skew Constraints.
Signals |
Skew Constraints (ps) |
---|---|
dq/dm to dk_p/n |
±5 |
dq to qk_p/n |
±5 |
qvld to qk_p/n |
±5 |
dk_p/n to ck_p/n |
±5 |
addr/cmd to ck_p/n |
±5 |
Differential signals p to n |
2 |
Notes: 1.For skew specifications, refer to the General Memory Routing Guidelines items 3–8. |
IMPORTANT: FPGA package flight times must be included in both total length constraints and skew constraints. When minimum and maximum values are available for the package delay, use the midrange between the minimum and maximum values. Memory device package flight times do not need to be factored in because their variances have been accounted for in these guidelines.