I have some question about the reference clock.
I am looking at the User Guide of SD3GDAEVK.
LMH0346 schematic uses "ABRACON ABMM-27.000MHZ-B2-T" crystal.
Do you have any other proven crystal information ?
* I am understanding the required specification, Datasheet p.13 "Table 3"
When using XO for Reference Clock, I believe XO CMOS 27MHz clock should be input to XTAL IN / EXT CLK pin.
Can you just leave XTAL OUT pin OPEN ?