DAC minimum reference voltage? is it just a guide line? why????

[SArepairman]

Why do DAC chips have a minimum reference voltage?
I have a DAC that I like in mind but it says the minimum reference voltage is 1V. Why won't it work with say 100mV reference? Why do DACs have a minimum reference voltage requirement? My understanding of their operations (built a discrete DAC once) tells me that they should not have this requirement.

[qno]

Maybe look at  the noise figures.
Below a 1V reference the LSB is lower than the noise.

[SArepairman]

if thats the case then I am fine.   
A moving noise band is just fine with me.

I also read there might be gain errors if the minimum voltage is lower then the specification.

Is there anything else to watch out for?

[qno]

I guess not.
I one used a DAC as an attenuator.
Put an  biassed AC voltage on the reference and select the amplitude with the DAC.
It woked fine, only lower output levels sufferd S/N distortion.

[madires]

Resolution and accuracy. Based on the design of the DAC it might not support such small steps.

[SArepairman]

Resolution and accuracy. Based on the design of the DAC it might not support such small steps.

can you elaborate?

[SeanB]

Some use the reference to drive transistors ( or FETs) switched inside the unit, and below the minimum level they do not turn fully on ( or off) enough to operate properly, giving rise to either a varying offset voltage and spurious outputs. To use a DAC with low voltage you need one with either a 4 quadrant reference input or one designed to be used as a variable attenuator.

Otherwise use a level above the minimum and divide the output down to the desired level using a buffer opamp and a resistive divider, or a fractional gain opamp circuit.