System Memory Design Guidelines (DDR-SDRAM)
R
142
Intel
®
855PM Chipset Platform Design Guide
Figure 80. Command Signal to SCK/SCK# Trace Length Matching Requirements
SO-DIMM0
Intel 855PM
MCH Package
= Motherboard Trace Lengths
SCK[2:0]
SCK#[2:0]
Note: CMD Lengths are measured from MCH-M
pins to SO-DIMM0 connector pads.
CMD Length = Y
SCK/SCK#[2:0] Length = X
SO-DIMM0 SO-DIMM1
Intel 855PM
MCH Package
SCK[5:3]
SCK#[5:3]
SCK/SCK#[5:3] Length = X
Note: CMD Lengths are measured from MCH-M
pins to SO-DIMM1 connector pads.
SMA[12:0],
SBS[1:0],
RAS#, CAS#,
WE#
= Motherboard Trace Lengths
SMA[12:0],
SBS[1:0],
RAS#, CAS#,
WE#
( Y - 1.0" ) < = X < = ( Y + 0.5" )
CMD Length = Y
( Y - 1.0" ) < = X < = ( Y + 0.5" )
