Intel 855GME

January 2007 149
Intel
®
855GME Chipset and Intel
®
6300ESB ICH Embedded Platform Design Guide
System Memory Design Guidelines (DDR-SDRAM)
Length range formula for DIMM1:
X
1
= SCK[5:3]/SCK[5:3]# total reference length, including package length. Refer to Section 5.4.1
for more information.
Y
1
= SMAB[5,4,2,1] total length = GMCH Package length + L1, as shown in Figure 73, where:
(X
1
– 1.5”) ≤ Y
1
≤ (X
1
- 0.5”)
No length matching is required from DIMM1 to the termination resistor. Figure 74 depicts the
length matching requirements between the CPC signals and clock. A nominal CPC package length
of 500 mils may be used to estimate baseline Mbyte lengths.
Figure 74. CPC Signals to Clock Length Matching Diagram
DIMM0
GMCH Package
SMA[5,4,2,1]
SCK[2:0]
SCK#[2:0]
N
ote: All lengths are measured from GMCH
d
ie pad to DIMM connector pad.
CPC Length = Y0
Clock Reference Length = X0
DIMM0
DIMM1
SCK[5:3]
SCK#[5:3]
Clock Ref Length = X1
N
ote: All lengths are measured from GMCH
d
ie pad to DIMM connector pad.
SMAB[5,4,2,1]
CPC Length = Y1
(X0 – 1.5") <= Y0 <= (X0 - 0.5")
(X1–1.5") <= Y1 <= (X1-0.5")
GMCH Package
855GME
GMCH
Die
855GME
GMCH
Die