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
Содержание Xeon
Страница 24: ...Introduction 24 Design Guide This page is intentionally left blank ...
Страница 30: ...Component Quadrant Layout 30 Design Guide This page is intentionally left blank ...
Страница 34: ...Platform Stack Up and Component Placement Overview 34 Design Guide This page is intentionally left blank ...
Страница 52: ...Platform Clock Routing Guidelines 52 Design Guide This page is intentionally left blank ...
Страница 66: ...System Bus Routing Guidelines 66 Design Guide This page is intentionally left blank ...
Страница 118: ...Intel 82870P2 P64H2 118 Design Guide This page is intentionally left blank ...
Страница 146: ...I O Controller Hub 146 Design Guide This page is intentionally left blank ...
Страница 148: ...Debug Port 148 Design Guide This page is intentionally left blank ...
Страница 210: ...Schematic Checklist 210 Design Guide This page is intentionally left blank ...
Страница 220: ...Layout Checklist 220 Design Guide This page is intentionally left blank ...
Страница 222: ...Schematics 222 Design Guide This page is intentionally left blank ...