IEI Integration ICE-DB-9S - Manual (Page 77)

ICE Module
Page 64
4.6.4 LVDS Routing Guideline
4.6.4.1 Impedance
Table 4-16: LVDS Impedance Consideration
Parameters Routing
Transfer Rate 5.38 Gbits/sec
Maximum signal line length to the LVDS connector (coupled
traces)
8.75 inches
Signal length used on COM Express module (including the
COM Express" carrier board connector) "
2.0 inches
Signal length to the LVDS connector available for the COM
Express carrier board "
6.75 inches
Differential Impedance 100 Ohms +/-20%
Single-ended Impedance 55 Ohms +/-15%
Spacing between pair to pairs (inter-pair) (s) Min. 20mils
Spacing between differential pairs and high-speed periodic
signals
Min. 20mils
Spacing between differential pairs and low-speed non
periodic signals
Min. 20mils
Length matching between differential pairs (intra-pair) +/- 20mils
Length matching between clock and data pairs (inter-pair) +/- 20mils
Length matching between data pairs (inter-pair) +/- 40mils
Spacing from edge of plane +/- 40mils
4.6.4.2 Implement
Many carrier board designs do not need the full range of LVDS performance offered
by COM Express modules. It depends on the flat panel configuration of the COM
Express module, as well as the carrier board design, as to how many LVDS signal
pairs are supported. While the dual channel 24-bit LVDS configuration needs all 10
LVDS signal pairs, a single channel 18-bit LVDS configuration only requires 4 LVDS
signal pairs. In this case all unused LVDS signal pairs should be left open on the
carrier board. If the LVDS display interface of the COM Express module is not
implemented, all signals associated with this interface should be left open.