"The origin of the split GND approach comes from the need to keep separated return currents for analog and digital subsystems. The separation between the two subsystems can be achieved by a physical separation of the two grounds (real cut) or by a spacial separation of them. When using more than one mixed signal IC with common GND connections for analog and digital signal the approach of having separate grounds may cause more issues compared to a single GND configuration. [...] Additionally, the use of a split GND plane can create other problems because of the presence of possible multiple return paths of the supply current, and consequently of possible current loops. The supply current must return through a common ground terminal to which both the analog and the digital sub subsystem are referenced. The presence of the current loop will generate radiated emission, with the emission level being proportional to the loop area and to the current intensity. " (chapter 9.Mixed signal PCB layout of AN5043)
My advise is to use a single GND, as you can also see on the DataSheet (Figure 1 and 2).
Best Regards,
Pierre
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