Guideline: Use Series Termination Resistor
You can significantly reduce voltage overshoot by matching the impedance of the driver to the characteristic impedance of the transmission line.
If the driver device manufacturer specifies the driver buffer output impedance, you can use the following equation to determine the apropriate series termination value:
R driver+R series≈Z 0
- R driver represents the intrinsic impedance of the driver
- R series represents the resistance of the external series resistor
If the output impedance value of the driver is not available, you can run simulation with an IBIS model for the driver to determine the appropriate series termination resistor value for the interface.
Some drivers offer series on-chip termination (OCT) to minimize impedance mismatch to the transmission line. You can select a driver with R driver that closely matches the transmission line impedance in such cases. OCT provides sufficient impedance matching without the expense of additional external component.
Did you find the information on this page useful?