This Figure shows the data signals (DQ, DM, and DQS) point-to-point for DDR3 SDRAM.
Table: DDR3 SDRAM Impedance, Length, and Spacing Guidelines for Data Signals shows the DDR3 SDRAM impedance, length, and spacing guidelines for data signals.
Parameter |
L0 |
L1 |
L2 |
Units |
---|---|---|---|---|
Trace type |
Stripline |
Stripline |
Stripline |
– |
dq single-ended impedance Z0 |
50±10% |
39±10% |
50±10% |
W |
dqs differential impedance ZDIFF |
86±10% |
76±10% |
86±10% |
W |
Trace width (nominal) |
4.0 |
6.0 |
4.0 |
mil |
Differential trace width/space/width |
4.0/4.0/4.0 |
6.0/6.0/6.0 |
4.0/4.0/4.0 |
mil |
Trace length (nominal) |
0.0~5.0 |
0.0~0.1 |
inches |
|
Spacing in byte (minimum) |
4.0 |
8.0(2) |
4.0 |
mil |
Spacing byte to byte (minimum) |
4.0 |
20 |
4.0 |
mil |
dq to dqs spacing (minimum) |
4.0 |
20 |
8.0 |
mil |
Spacing to other group signals (minimum) |
8.0 |
30 |
30 |
mil |
Maximum PCB via count |
2 |
– |
||
Notes: 1.See item 2 in General Memory Routing Guidelines. 2.If greater than 1.5 inches is needed in the breakout area, change L1 spacing to 12.0. |