Design Guide
71
Memory Interface Routing Guidelines
NOTES:
1. Indicated lengths measure from the MCH pin to the DIMM connector pin (including the series resistor).
Table 6-3. Source Synchronous Signal Group Routing Guidelines
Parameter
Intel
®
E7500
Reference
Signal Group
DQ[63:0], CB[7:0], DQS[17:0]
Topology
Daisy Chain
Reference Plane
Ground
MCH to Rtt (Zo)
50
Ω
± 10%
MCH to Rtt Trace Width
5 mil
Nominal Trace Spacing
15 mil
Trace Length – MCH to DIMM1
1.8” to 6.0”
Trace Length – Rs to DIMM1
< 0.8”
Trace Length – DIMM to DIMM
0.8” to 1.2”
Trace Length – DIMM to Rtt
< 0.8”
Series Resistor (Rs)
10
Ω
± 2%
Termination Resistor (Rtt)
22
Ω
± 2%
MCH Breakout Guidelines
5/5, < 500 mil
Length Tuning Requirements
DQ to DQS: ± 100 mil
DQS to CMDCLK pair: ± 1750 mil
Figure 6-4. Source Synchronous Topology
DIMMs
DQ/CB Data Group
Associated DQS
DQ/CB Data Group
Associated DQS
MCH
DIMM to
DIMM
DDR VTERM
(1.25V)
Intel
®
MCH to DIMM1
Rs
Rs
Rs
Rs
Rtt
Rtt
Rtt
Rtt
Rs to
DIMM1
DIMM to
DIMM
DIMM to
DIMM
DIMM
to Rtt
Содержание Xeon
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