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adc input rangge for sm320f2801

Prodigy 130 points

Replies: 3

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Hi need to know the ppm and tolerance of the internal adc reference . I am using SM320F2801-ep . I also need to know if i use the external reference for entire range of 3V is it possible for me to give 2.048V reference or i will have to give 1.5V reference to get the full 3V analog input range

 

regards

 

Rony

 

 

 

  • The internal reference drift over temperature (in PPM) is listed in the data sheet, document SGLS316A, in the ADC electrical characteristics table.  

    Note that the other ADC spec's are min/max over VTP, which includes variation due to drift in the internal reference.

    The ADC range is always 0-3V for this device.  This applies to the internal reference as well as 1V, 1.5V, and 2V external references.  

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  • In reply to Devin Cottier:

    Hi Devin

     

    ThankYou for sharing the same . The datasheet says 50 ppm but i din see the tolerance .I am also curious to understand how the ADC maintains it  range for different input reference . Is it a hybrid architecture that is used from sigma delta type ADC that enables this. Can you share any article which shows this explanation

     

    Regards

     

    Rony

  • In reply to RONY MATHEW:

    We do not spec' the absolute value of the internal bandgap voltage reference, just the relative temperature drift.  This is to give a better understanding of how the error specs (particularly gain error) will move within their min/max specs.  

    When you supply each of the 3 external reference voltages, you will need to specify which voltage is selected in the REFSEL register.  From this, the ADC uses internal circuitry to derive the required internal levels from each of the possible external levels.  

    The converter architecture of the F2801 ADC is pipelined. It is not similar to sigma-delta type converters. 

     

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