For the AD5643R DAC, when the internal reference is used, the full scale output range is 2x the reference voltage. I am wondering if when an external reference is used, if the full scale output range is also 2x the external reference voltage, or if the range is just ground to the reference voltage? It is not clear from the data sheet. Can I get a 0V to 0.8V full scale range from this part? Thanks.