I'm a little confused after browsing datasheet and reference manual. I couldn't find information about the voltage level of external clock for the cpu. In my current desigh there are many ICs required clocking, so I decided to use programmable PLL-based synthesizer with multiple outputs, like CDCE925, CDCE949.
Do I have to use VDD level clock ? I have a lot of experience with ARM based MCUs, and a lot of them require 1.8V level external clock signal. There is no information regarding the external clock voltage level in the datasheets exposed on the web site.
If you read the Data Sheet there is a specification for all digital inputs.
P Input high voltageall digital inputs
VIH VDD > 2.7 V 0.70 x VDD VDD > 1.8 V 0.85 x VDD