I like to implement a serie resistor on RO output signal (pin 1) when using 50R transmission lines for good signal integrity. Hence the following questions:
1. Is there any IBIS model available to the LTC1685 transceiver?
2. What is the approximate output impedance of the RO output signal?
unfortunately we do not have IBIS model for this part. A way to roughly estimate the output impedance is via the output logic threshold.
VOH is specified with VDD=5.0V, Io=4mA, then Ro could be calculated by (5.0 V - 4.8 V) / 4mA = 50 ohm.