AD7606C-18

So, im using the ad7606c-18 instead of the -16, and I use a SCLK with 16.67 MHz and works correctly, but when I increase it to 25 MHz it does not work. I'm using the EVAL-AD7606C18FMCZ board.

Another question that I have, if you know if the FlexSPI from NXP LS1028 can be adapted to this serial protocol?, I think we cannot, just to confirm.

And what SPI protocol has more than one MISO signal?

Thanks.