System Memory Design Guidelines (DDR-SDRAM)
R
Intel
®
855PM Chipset Platform Design Guide
137
Figure 77. Control Signal to SCK/SCK# Trace Length Matching Requirements
SO-DIMM0
Intel 855PM
MCH Package
= Motherboard Trace
Lengths
SCS#[1:0],
SCKE[1:0]
SCK[2:0]
SCK#[2:0]
Note: Lengths are measured from MCH-M pins to SO-
DIMM0 connector pads.
CNTRL Length = Y
SCK/SCK#[2:0] Length = X
SO-DIMM0 SO-DIMM1
= Motherboard Trace
Lengths
SCK[5:3]
SCK#[5:3]
SCK/SCK#[5:3] Length = X
Note: Lengths are measured from MCH-M pins to SO-
DIMM1 connector pads.
SCS#[3:2],
SCKE[3:2]
CNTRL Length = Y
( Y - 1.0" ) < = X < = ( Y + 0.5" )
( Y - 1.0" ) < = X < = ( Y + 0.5" )
Intel 855PM
MCH Package
