Hi there,
but you massively loose resoution when using a 5V reference. Thats why in AN1154 a 2V regulator is used. I just thought that maybe the Vref from the Arduino was used to implement the suggested design. Anyhow, I'm trying to fetch a 2V regulator as one should be enough for a 2 Channel application.
But Im curious, did you measure the accuracy of your setup?
Greetings,
Jan