Mobile Intel Pentium 4 Processor - M and Intel 845MP/MZ Chipset Platform Design Guide

Mobile Intel
®
Pentium
®
4 Processor-M and Intel
®
845MP/845MZ Chipset Platform
74 Design Guide
R
5.2.3.2.2. Command Group Signal Length Matching Requirements
The command signals, must be 1.0 inch to 3.0 inches shorter than their associated differential clock pairs
SCK/SCK#[5:0].
Note that these requirements may change in a later revision of the design guide based on a post silicon
simulation analysis.
Length matching equation for SO-DIMM0:
X
1
=SCK/SCK#[2:0]
Y
1
=L1 +L2 of Figure 34 where,
( X
1
– 3.0” ) ≤ Y
1
≤ ( X
1
– 1.0 inch )
Length matching equation for SO-DIMM1:
X
2
=SCK/SCK#[5:3]
Y
2
=L1+L3 of Figure 34 where,
( X
2
– 3.0” ) ≤ Y
2
≤ ( X
2
– 1.0 inch )
For example if the clock length of SCK/SCK#[2:0](X
1
) is 3.0 inches then the length of all command
signal routing to SO-DIMM0 must be between 0.75 inches to 2.0 inches, if SCK/SCK#[5:3](X
2
) is 3.5
inches then the length of all command signal routing to SO-DIMM0 must be between 0.5 inches to 2.5
inches. The minimum length of 0.75 inches for command signal routing is the shortest possible length to
SO-DIMM0.
Caution: The MCH-M package lengths don’t need to be taken into account for routing purposes.
The diagram below depicts the length matching requirements between the command signals and the
clock signals.