Hello,
Is the thermal pad supposed to be connected to the ground plane? I haven't found anything in the datasheet addressing if it is connected electrically. If it can be connected to the ground plane, what are the thermal drift implications on the internal voltage reference?
The ADS8681WEVM schematic has the pad floating and the top layer image (layer 1) shows it isn't connected to the ground pins, but the ground plane image (layer 2) looks to have a cross pattern of 5 vias under the pad.