Question
I'm going to use two parts into a board, and the sampling clocks for both DACs
are sourced by the same clock distribution module. So the synchronization is
inherent to the system architecture as the sampling clocks
re synchronized. May I leave SYNC_OUT and SYNC_IN pins unconnected?
Answer
Synchronization of multiple AD9739’s imply that each of the DAC’s outputs are
time-aligned to the same phase when all devices are fed with the same data
pattern (with DCI) at the same instance of time(with phase aligned DACCLK
signals). The main contributor to phase ambiguity between devices is from the
Div-by-4 circuitry within the digital path of the LVDS Data Receiver and Data
Assembler (refer to figure 82). Upon power-up, the state of this internal
divider is unknown hence the need to employ a synchronization method that phase
aligns the digital paths of the AD9739 with respect to each other.
If this is not required, then one does not need to use the SYNC_IN and SYNC_OUT
pins.