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Tool/software:
Hello,
We are having some cunfusion on the polarity of the analog inputs and what would the corresponding values that the SDFM module would read.
Asuming th SDFM module is configured with as OSR of 33 in 16 bit integer format the maximum values come out to be (+17968 to -17968)
So 50mv differential corresponds to 17968 count and
-50mv differential corresponds to -17968 count
Consider this simplified circuit in the data sheet:
When the data sheet says 'Differential input voltage', it means V(AINN) - V(AINP) OR V(AINP) - V(AINN)?, Could you please confirm this?
Looking at the simplified schematic if the Top switch is turned on and voltage at AINN pin is greater than voltage at AINP, is it correct to say that the bit stream would represent positive values after the SDFM modules decimation filters?
Hi AK,
Thank you for your question. Differential input voltage is AINP-AINN.
If the value of AINN is greater than AINP the bit stream should represent a negative value up until the clipping voltage (-64mV). Past the clipping voltage (+/-64mV), the output will show nonlinear behavior - a stream of only zeros and a one every 128 cycles to indicate proper device function.
Best regards,
Eva