ADC168M102R-SEP: What is recommended termination for CS', CLOCK, BUSY, SDI, RD, SDOA, SDOB, CONVST?

Hi Charles,

For the most part, assuming relatively short trace lengths and fast rise and fall times (<5ns), we recommend 22-50Ω series termination resistors in order to avoid ringing and overshoot from fast signal edges.

SPI/serial lines don't necessarily require 50Ω characteristic trace, but it is common to design for it. If that's the case on your board, then you can place a 50Ω resistor near the driver to match the trace impedance. 

Regards,
Joel