The stepsize (DA conversion) depends on the resolution.

If you have a 8 bit DA convertor with VRef 1.28 V then your step size is 0,005V

if you have 1V as ref -> 0.0039 V

if you have 0.64V -> 0.0025 V

8bits represent 256 steps (2^8), each step must be Vref/steps Volt = stepsize.

so if you have 10bit -> 1024 steps

1.28V ref -> 0.00125 V stepsize
1V ref -> 0.000976 V stepsize
0.64V ref -> 0.000625 V stepsize

All close to Noise. So guard your signals and VCC/GNd very good !!


Bert Regards