ADC3908S125: Timing: Synchronicity between two ADCs

Part Number: ADC3908S125

Hi, We are plannig to use two ADC3908S125 in our design  with the same sample clock. We need to make sure the output of the two ADCs has valid data before triggering a write operation on the mamemory.  Based on the datahseet, the Propagation delay (Tpd) for each ADC is Ts/4+3ns. Our question  what is the variation in Tpd ?

Appreacite your input.

Thanks