Using the ADN2915 to generate PRBS in LTR without PIN driven

Is it possible to use the ADN2915 to generate PRBS patterns when the PIN / NIN are floating?  The datasheet doesn't mention that PIN needs to be driven but we can't get our design to put out PRBS above 2.5G with any reliability while in LTR mode and I just noticed that the ADI-BERT design which utilizes ADN2915s for this purpose always drives PIN and REFP when in lock to reference mode.

We're driving our RefClk P/N with an AC coupled Si544 using the LVDS I/O standard.

Thank you for any support you can provide.

~Andy