LMH6551: Sequence with post ADC

Hi team,

I would like to ask about two things related to common mode voltage input VCM.

1, When using ADS4225 as post ADC and common mode output of ADC is routing to VCM pin of LMH6551, Is the VCM Hi-Z before ADC turns on?

2, When there is no input on the VCM pin, Does the LMH6551 output nothings?

Those two questions are because customer would like to decide whether ADC input protection is required or not before ADC AVDD has rise up.

Regards, 

Hideki