Noise is increased as I swtich from chop to non-chop mode. Why?
There will be a reduction in modulator noise of about 20-30% when the AD7730 is
used in non-chop mode compared to chop mode. However, when the AD7730 is used
in non-chop mode there will be a reduction in drift performance. Most weigh
scale applications will use the AD7730 in chop mode for increased drift
For the best line frequency rejection, you should set the output update rate to
be equal to the line frequency. The position of the first notch in the digital
filter is equal to the output update frequency.