AD9361 Clock input


I'm using an AD9361 chip and want to use a tight tolerance TCXO, but I have some questions.


According to the datasheet the typical peak to peak voltage is 1.3V.

According to the user manual the maximum peak to peak voltage is 1.3V.


On the EVAL-AD-FMCOMMS5-EBZ Evaluation board (Drawing number 02_038176), found here:


There is a CMOS input of 1.8V, ac coupled.


This seems to contradict the spec?  Is a 1.8V CMOS ac coupled input allowed?