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How to derive the parameters Offset Voltage and Gain Error from AD7663 datasheet?

Question asked by jebaspaul on Nov 27, 2013
Latest reply on Dec 3, 2013 by KarenNE

Hi,

 

I am using AD7663 in my Multi-Channel DAS. My input signal is Bipolar, +/-10V. I need to estimate the Offset and Gain error associated with AD7663. These errors are not explicitly mentioned in the datasheet. I tried to attain those parameters as following;

 

Bipolar zero error : 0.06% of FSR - It is not mentioned that this error is inclusive of Gain error or not. If it is inclusive of Gain error then how to find the Offset error.

 

Bipolar Full scale error : +/-0.25% of FSR - It is not mentioned clearly whether it is inclusive of Offset error or not.

 

Pg:11, TPC-15, has information about Offset voltage. Please confirm that the TPC-15 illustrates the input referred offset voltage of AD7663.

 

If suppose I derive Offset voltage error from TPC-15, it comes around 0.0046% at +85DegC(i.e 3 LSB error). After the estimation of Offset error the Gain error is calculated as +/-0.245%. (+/-0.25% - +/-0.0046%)

 

Therefore, the maximum Gain error can be translated to 161 LSB. [0.245 * 20V/(100 * 1LSB) = 161 ; where 1LSB = 20/2^16].

 

Please confirm the calculation.

 

And also if there is any test results related to the external reference please share with me. It would be useful in error estimation.

 

If possible please explain the graph TPC-15. I couldn't understand the exact illustration of that graph.

 

 

Thanks,

Jebas.

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