EJ8xxx - Signal-Distribution-Board for standard EtherCAT plug-in modules

Impedance and Routing

The following points should be taken in to account during the PCB design phase:

The E-bus traces have to be routed in inner layers.
The differential impedance of the LVDS traces shall be 100 Ω.
Width and spacing of the differential signal are depending on the concrete layer stack up and have to be calculated individually.
The differential signals should be routed as edge coupled traces.
The distance between the differential pairs should be three times larger than their inner distance (see following Figure (D)).
Differential pairs should be routed without Vias (vertical interconnect access), in order to avoid impedance jumps.
Maximum values for uncoupled trace and overall trace length can be found in the specification for LVDS signals ANSI/TIA/EIA-644 „Electrical Characteristics of Low Voltage Differential Signaling (LVDS)
Differential pair spacing
 
Note
Avoid shor circuits
Pay attention to short circuits when configuring the cross-section!