160
Intel
®
855GME Chipset and Intel
®
6300ESB ICH Embedded Platform Design Guide
Integrated Graphics Display Port
6.2.2
LVDS Routing Guidelines
The traces associated with the LVDS Transmitter timing domain signals are differential traces
terminated across 100
Ω
± 15
Ω
and shall be routed as:
•
Strip-line only.
•
Isolate all other signals from the LVDS signals to prevent coupling from other sources onto the
LVDS lines.
•
Use controlled impedance traces that match the differential impedance of your transmission
medium (i.e., cable) and termination resistor (Note: the transmission medium’s Zdiff shall be
maintained to 100
Ω
± 15 percent).
•
Run the differential pair trace lines as close together as possible as soon as they leave the IC,
not greater than 10 mils. This helps eliminate reflections and ensure noise is coupled as
common mode. Plus, noise induced on the differential lines is much more likely to appear as
common mode, which is rejected by the receiver.
•
The LVDS transmitter timing domain signals have a maximum trace length of 10.0 inches.
This maximum applies to all of the LVDS transmitter signals.
•
Traces must be ground referenced and must not switch layers between the GMCH and
connector.
Table 46. LVDS Signal Group Routing Guidelines
Parameter
Definition
Signal Group
LVDS
Topology
Differential Pair Point to Point
Reference Plane
Ground Referenced
Differential Mode Impedance (Zdiff)
100
Ω
±
15%
Nominal Trace Width
4 mils
Nominal Pair Spacing (edge to edge)
7 mils
Minimum Pair to Pair Spacing
(See exceptions for breakout region below.)
20 mils
Minimum Serpentine Spacing
20 mils
Minimum Spacing to Other LVDS Signals
(See exceptions for breakout region below.)
20 mils
Minimum Isolation Spacing to non-LVDS
Signals
20 mils
Maximum Via Count
2 (per line)
Package Length Range – P1
550 mils
±
150mils
(Refer to
for exact lengths.)
Total Length –
Max 10”
Clock Length Matching
Match all segments to ± 20 mils (Refer to
for
more information.)
Clock to Clock Length Matching (Total Length)
Match clocks to X0
±
20 mils
Breakout Exceptions
(Reduced geometries for GMCH breakout
region)
Breakout section shall be as shorter as possible. Try to
maintain trace width as 4 mils, spacing 7 mils, while the
spacing between pairs may be 10-20 mils.
Summary of Contents for 6300ESB ICH
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