PCB traces should be terminated when the trace length exceeds the following condition: Originally posted in cdnusers.org by satya1234
Length > tr / (2 x t pd )
Where tr = Signal rise time, t pd = Signal propagation delay.
Most used termination types:
Series [Source] Termination :
should only be used with one load on the line, but only requires one resistor [R], placed near the source.
Parallel Termination :
Used with any number of loads.Requires one resistor,placed near the receiver.
Thevenin Termination [or Split Termination]:Placed near the receiver.