System Memory Design Guidelines (DDR-SDRAM)
R
Intel
®
855PM Chipset Platform Design Guide
153
Figure 87. Clock Pair Trace Length Matching Requirements
1
SO-DIMM0
Intel 855PM
MCH Package
= Motherboard Trace Lengths
Note: Lengths are measured from MCH-M pin to SO-DIMM0
connector pads.
SCK/SCK#[0]
SCK/SCK#[1]
SCK/SCK#[2]
SO-DIMM0
SO-DIMM1
SCK/SCK#[3]
SCK/SCK#[4]
SCK/SCK#[5]
Note: Lengths are measured from MCH-M pin to SO-DIMM1
connector pads
= Motherboard Trace Lengths
Intel 855PM
MCH Package
Max (X
0
,X
0#
,X
1
,X
1#
,X
2
,X
2#
) - Min (X
0
,X
0#
,X
1
,X
1#
,X
2
,X
2#
) <= 0.025 inches
Max (Y
0
,Y
0#
,Y
1
,Y
1#
,Y
2
,Y
2#
) - Min (Y
0
,Y
0#
,Y
1
,Y
1#
,Y
2
,Y
2#
) <= 0.025 inches
SCK/SCK#[0] Length = X
0
/X
0#
SCK/SCK#[1] Length = X
1
/X
1#
SCK/SCK#[2] Length = X
2
/X
2#
SCK/SCK#[5] Length = Y
2
/Y
2#
SCK/SCK#[3] Length = Y
0
/Y
0#
SCK/SCK#[4] Length = Y
1
/Y
1#
NOTE:
Length matching between DQS and Clock pairs must include package length.
