Memory Interface Routing Guidelines
76
Design Guide
6.5
Chip Select Routing
The MCH provides eight chip select signals. Two chip selects must be routed to each DIMM (one
for each side). The E7500 chip selects for each DIMM must be length matched to the
corresponding clock within ± 2.0 inches and require parallel termination resistors (Rtt) to DDR
VTERM, placed within 3 inches of their associated connector.
NOTES:
1. For 3-DIMM solutions, treat CS6# and CS7# as a no connect.
2. Indicated lengths measure from the MCH pin to the DIMM connector pin, and from the DIMM connector to
the parallel termination resistor pin.
Table 6-6. Chip Select Routing Guidelines
Parameter
Intel
®
E7500
Reference
Signal Group
CS[7:0]#
Topology
Point to Point
Reference Plane
Ground
Trace Impedance (Zo)
50
Ω
± 10%
Nominal Trace Width
5 mil
Nominal Trace Spacing
15 mil
Trace Length – MCH to DIMM1
1.8” to 9.6”
Trace Length – MCH to DIMM2
1.8” to 9.6”
Trace Length – MCH to DIMM3
1.8” to 9.6”
Trace Length – MCH to DIMM4
1.8” to 9.6”
Trace Length – DIMM to Rtt
< 3.0”
Termination Resistor (Rtt)
22
Ω
± 2%
MCH Breakout Guidelines
5/5, < 500 mil
Length Tuning Requirements
To CMDCLK pair: ± 2.0”
Figure 6-11. Chip Select Topology
CS0#
CS1#
CS2#
CS3#
CS4#
CS5#
CS6#
CS7#
MCH
DDR VTERM (1.25V)
DIMMs
Rtt
MCH to DIMM
DIMM
to Rtt
Summary of Contents for Xeon
Page 24: ...Introduction 24 Design Guide This page is intentionally left blank ...
Page 30: ...Component Quadrant Layout 30 Design Guide This page is intentionally left blank ...
Page 52: ...Platform Clock Routing Guidelines 52 Design Guide This page is intentionally left blank ...
Page 66: ...System Bus Routing Guidelines 66 Design Guide This page is intentionally left blank ...
Page 118: ...Intel 82870P2 P64H2 118 Design Guide This page is intentionally left blank ...
Page 146: ...I O Controller Hub 146 Design Guide This page is intentionally left blank ...
Page 148: ...Debug Port 148 Design Guide This page is intentionally left blank ...
Page 210: ...Schematic Checklist 210 Design Guide This page is intentionally left blank ...
Page 220: ...Layout Checklist 220 Design Guide This page is intentionally left blank ...
Page 222: ...Schematics 222 Design Guide This page is intentionally left blank ...