Length Matching Formulas Between Ep80579 And Ddr2 Sodimm - Intel EP80579 Manual

A.4.2 Package Length Compensation
Package length compensation is required for total routing length requirements, see the
length matching rules listed in
and DDR2 SODIMM" on page
®
Intel EP80579 Integrated Processor Product Line Datasheet.
A.4.3 Length Matching and Length Formulas
The routing guidelines presented in the following subsections define the recommended
routing topologies, trace width, spacing geometries, and absolute minimum and
maximum routed lengths for each signal group. These guidelines are recommended to
achieve optimal signal integrity and timing.
Table A-5.

Length Matching Formulas between EP80579 and DDR2 SODIMM

Source/
Destination
EP80579 Pad to
DDR2 SODIMM
Notes:
1. Length matching is only required within each Byte lane. Signal length matching is not required
outside the Byte lane. For example, any signal within DQ [0:7] need not be length matched to DQS
[3].
2. Total length means - L
A.4.4 DDR2 Interface System Interconnect
Figure A-1
DDR2 Memory Controller and the SODIMM for the signal groups provided in
The Command/Address and Control signals require external terminations. External
terminations are not required for DQ and DQS signals since both the EP80579 and the
SDRAMs contain internal ODT. The following sections provide the detailed topology and
routing guidelines for each of the signal groups.
®
Intel EP80579 Integrated Processor Product Line
Platform Design Guide
320
®
Intel EP80579 Integrated Processor Product Line—System Memory Interface (SODIMM)
Table A-5, "Length Matching Formulas between EP80579
320. See the DDR2 package length information in the
Signal Group to matching
signal
DQS to DQ/DM
DQS to clock
CMD/ADD to Clock
CTRL to CMD/ADD
Clock to Clock#
+ L
PKG BREAK
provides a block diagram of the system interconnect between the EP80579
Total Length Matching Tolerances
Min DQS = Min(DQ/DM) - 200 mils
Max DQS = Max(DQ/DM) - 200 mils
DQS = CLK/CLK# ± 500 mils
CMD/ADD = CLK/CLK# ± 20 mils
Total CTRL Length = Total (CMD/ADD
Length) + 3.0 inches
CLK[x] = CLK[x]# ±10 mils
+ L
ROUTE
Notes
1, 2
2
2
2
2
Table A-4.
May 2010
Order Number: 320068-005US