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ADS1015 - Relation between VDD and Output Code

Kawai
Guru 19785 points

Hi, I have a question about ADA1015.

Reading datasheet and E2E, I found that this device have virtual reference.

Please let me confirm if my following recognitions are correct.

1) FSR(Virtual Reference) is set by PGA setting, VDD does not affect FSR.

2) The output code would be the same value even if the VDD changes, If the input signal is the same.

    --> For example,  design with VDD=3.3V or 5.0V would have same output code if the input votage is the save value.

 

Best Regards,

Kawai

  • 0
    TI__Guru** 113765 points

    Hi Kawai,

    That is almost correct.  VDD does effect the potential code output depending on the scale selected.  You can never measure an input that exceeds VDD.  If the full-scale range is +/-4.096V, you can read full scale at 5V, but not at 3.3V.  However, in the case of +/-2.048V you can reach full-scale from both 3.3V and 5V and the resultant code is the same.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Guru 19785 points

    Hi Bob-san,

    Thank you for your reply.

    I understand that you will never measure an input exceeds VDD.

    I`m sorry to ask you again but please let me confirm my understanding.

    Let`s say that the full scale of +/- 4.096V is selected.

    If there is an  input of 1.0V, the output code at VDD=3.3V or 5.0V would be the same.

    Is this correct ?

    Thanks and Best Regards,

    Kawai

  • 0 in reply to Kawai
    TI__Guru** 113765 points

    Hi Kawai,

    Yes, that is correct.

    Best regards,

    Bob B