Kontron COMe Starterkit Eval T2 - Manual (Page 193)

Carrier Board PCB Layout Guidelines
6.6.3. LPC Trace Routing Guidelines
Table 71: LPC Trace Routing Guidelines
Parameter Trace Routing
Transfer Rate @ 33MHz 16 MBit/s
Maximum data and control signal length allowance for the
COM Express Carrier Board 15.0 inches
Maximum clock signal length allowance for the COM Express
Carrier Board 8.88 inches
Single-ended Impedance 55 Ω +/-15%
Trace width (W) PCB stack-up dependent
Spacing between signals (inter-signal) (S) PCB stack-up dependent
Length matching between single ended signals Max. 200mils
Length matching between clock signals Max. 200mils
Spacing from edge of plane Min. 40mils
Reference plane GND referenced preferred
Via Usage Try to minimize number of vias
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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