The AD9954 electrical specification provide both 1.8 & 3.3v parameters for DVDD_IO.
Noting that sync_clk rateis limited to 62.5Mhz at 1.8V
However the pin specification for DVDD_IO is: "Digital Power Supply. This pin is for I/O cells only, 3.3 V."
And then again in "Synchronizing Multiple AD9954s"
"Finally, the DVDD_I/O supply should be set to 3.3 V for all devices that are to be synchronized."
So can 1.8v be used for DVDD_IO our should the notes later in the datasheet about 3.3V only be adhered to?