Is there any additional information available to indicate at what temperature
this facility should be used?
The AD5554 is spec'd over -40 to 85 degC. The limits on the spec table is for
VSS=0V. If you are satisfied with the spec, biasing VSS to 0V should be fine.
The output leakage is slightly better when VSS is less than 0V. The FAB process
is well controlled, the difference in Iout leakage between VSS=0V and VSS=-5V
is very small over the temperature range, in the order of a few nA.