I'm not sure if this is the correct place to report this, but I can't find a more obvious place.
I've been trying to use the AD80066 in 4-channel mode. I got strange results for a long time (e.g. output value increasing as input voltage decreased) until I tried programming the Mux register differently.
The datasheet says "Bits D[3:0] are used when operating in 1-channel mode", and they have a default value of zero - implying that zero is an appropriate state for them. However, I only got sensible values from the converter in 4-channel mode when all four bits were set to 1. I think that the datasheet would be correct, and less misleading, were the sentence above simply removed.