Assuming I have single ad9954 on my board and it doesn't need to be synchronized:
1) I plan to turn off sync_clk output, what should I do with sinc_in pin?
2) Which synchrinization mode I need to configure?
3) I drive IO_UPDATE from async uController, I can't meet setup/hold requirment vs sync_clk (I can only make it wide), I dont really care if the update will ocour on the current or next sync_clk, do u see any problem.
4) I plan to work with refclk=100MHz, sysclk=400MHz, my output will be a 100MHz +/- upto 20KHz. after updating new FTW, will it output drift smotohly?