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I have questions about AD7175-2, but I beleive they would also valid for AD7172-2 and AD7177-2, so the answers would be relevant for their users too.

1. May the inputs be shared between the channels? E. g if Ain0 and Ain1 set up for differntial measurement on channel 0, may the Ain1 be used for single ended measurement on channel 1?
2. I am a bit confused about dat rate and channels. if the data rate is 100 SPS, would it mean 50 SPS effective rate with 2 channels?
3. For the reason of simplicity the ADC is to be used to measure following signals with full scale voltages:
1.  +/- 1 V bipolar differential signal. (eg channel 0)
2. 5 V unipolar pseudodifferintal (channel 1)

The b) forces to use 5 V external refernce, which is disadvantageous for measurement on channel 1. Luckily, the ADC has inetrnal 2.5 V reference, which could be used on channel 1 to bring it closer to optimum range. Would it make sense to do so?

I may have further questions as I move on with the programming.

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• Hello Jellenie,

At first a general note, I ask question that about what I could not understand from the data sheet. It is not helpful when you simply copy-paste from it, like you did with questions 7 and 8. Perhaps you just don't know the answer? Or you could ask a clarifiying question if I you don't understannd, what I am asking about.

7. So how do I calculate offset (register) from offset voltage and gain from the gain coefficient?

I would like clear separate formulas Offset=? and Gain=?

8.I need more information about system calibration. Do the voltages have to be applied to both pins? Do they need to be physically applied or the inputs could be simplöy switch to ground for offset calibration and to reference voltage for gain calibration?

10. I see I used "effective" somewhat misleadingly. What I really asked about is the unipolar mode mentioned on page 24. It says the format is straight binary, but I suspect that it is achieved by making it 2's complement and ignoring the - the negative range and thus the MSB, thus reducing the real resolution by 1 bit. Am I correct?

Thank you for your help

• Hello Jellenie,

At first a general note, I ask question that about what I could not understand from the data sheet. It is not helpful when you simply copy-paste from it, like you did with questions 7 and 8. Perhaps you just don't know the answer? Or you could ask a clarifiying question if I you don't understannd, what I am asking about.

7. So how do I calculate offset (register) from offset voltage and gain from the gain coefficient?

I would like clear separate formulas Offset=? and Gain=?

8.I need more information about system calibration. Do the voltages have to be applied to both pins? Do they need to be physically applied or the inputs could be simplöy switch to ground for offset calibration and to reference voltage for gain calibration?

10. I see I used "effective" somewhat misleadingly. What I really asked about is the unipolar mode mentioned on page 24. It says the format is straight binary, but I suspect that it is achieved by making it 2's complement and ignoring the - the negative range and thus the MSB, thus reducing the real resolution by 1 bit. Am I correct?

Thank you for your help

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