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Original question:

ADS1282-SP: ADC Error Charachtristics is not clear

ADS1282-SP: ADS1282-SP Final FSR

Pouya TP
Prodigy 20 points
Other Parts Discussed in Thread: ADS1282-SP

Hello Everyone

I've configured  ADS1282-SP as below:

AVDD=5V
AVSS=0V
VREF=VREFP-VREFN= 2.5-0 = 2.5V

Signal: A DC signal in the range of 100mV - 150mV feeds to the diffential input and always AVINP > AVINN

In the datasheet the FSR is mentioned as FSR = ±VREF / (2 × PGA).

Question1 : would be my FSR according to my input and configuration?

While I use unipolar, should it be FSR=VREF / (2 × PGA)?? or it should be FSR=VREF/PGA?


Question2: The typical gain error is mentioend -1.0%. Should I apply this after considering the PGA ?
For exampe if input signal is :120mV and PGA=8, what would be the gain errorr of the signal?

  • +1
    TI__Mastermind 44670 points

    Hello Pouya,

    Question1 : would be my FSR according to my input and configuration?  While I use unipolar, should it be FSR=VREF / (2 × PGA)?? or it should be FSR=VREF/PGA?

    +FSR range will be VREF/(2*PGA).  In your case, you have VREF=2.5V.  If you are using PGA=1, then +FSR will equal 2.5(2*1)=+1.25V assuming no offset or gain errors.

    Question2: The typical gain error is mentioend -1.0%. Should I apply this after considering the PGA ?
    For exampe if input signal is :120mV and PGA=8, what would be the gain errorr of the signal?

    Yes, the gain error is total gain error from input to output code, including the PGA effects.  Assuming no other errors (INL, offset), 120mV input, the equivalent output code will be equal to 120mV*8*(1-1/100)=950.4mV.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    Prodigy 20 points

    I really apreciate your help.