• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 143 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS7924: Will the scale of ADI be maintained even if AVDD is not constant? Is there a built-in reference source?

user6082816
Prodigy 80 points
Part Number: ADS7924

Tool/software:

The reference voltage for ADS7924 is writen “Supply” on the TI web and the datasheet. Does the device generate a reference voltage internally from the voltage of AVDD pin? Does the ADI scale remains constant no matter how many volts I apply to AVDD within the recommended operating voltage range? As a specific example, if 2.2V is applied to ADI CH1, will the converted and output digital value be the same even if AVDD fluctuates in the range of 5.5V to 2.2V? For example, in the battery-powered case.

  • 0
    TI__Guru**** 175391 points

    Hi user6082816-san,

    Thank you for re-posting.  The ADS7924 ADC transfer function is described in section 7.3.4 of the datasheet.  The LSB size is directly related to AVDD, there is no internal 'reference' to account for any reduction there might be on the AVdd supply.  For your 2.2V input example, if AVdd is sourced from a battery and your input remains constant at 2.2V, the output code will increase towards full scale as the battery voltage discharges.

  • +1 in reply to Tom Hendrick
    Prodigy 80 points

    Hi,Tom,

    Thank you for your responce. I guess it is writen in section 7.3.5 of the datasheet, but I've understand that the LSB size is directly related to AVDD.