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INA3221 'conversion time'

Kevin Ginunas
Expert 6225 points

Other Parts Discussed in Thread: INA3221

Team,

I have a few questions regarding the ADC in INA3221, please see below.

1.       Is the “conversion” time really just a sample and hold?

2.       Does the “conversion” time essentially just produce more bits of accuracy to a sample and hold value?

3.       Does a 8ms “conversion” value take into account the signal for the entire 8ms? 

4.       Does the digital filter maintain precision with different “averaging” values?

Thanks for your support!

Best Regards,

Kevin Ginunas

  • 0
    TI__Genius 15770 points
    Hi Kevin,

    1. Yes, it is.
    2. Yes, it produce more bits of accuracy.
    3. Yes.
    4. Higher average, more accurate the result. Refer to Page 18 of the datasheet for more details.

    Regards,
    Mayrim
  • 0 in reply to Mayrim Verdejo
    TI__Expert 6225 points

    Hi Mayrim,

    A few more follow-on questions. If it would be easier to address this over the phone with the customer please give me a call.

    1. If it is a delta-sigma ADC, it is taking an integration over the entire sample period to produce a reading. Can you confirm the ADC architecture and these assumptions?  
    4. Note that the digital average takes the (new – old average) / divided by number in average.  This is a loss of precision unless there is compensating shifts not shown in the diagram.  Question is what is the full diagram with the compensation shifts or equivalent mechanism to maintain precision.

     

    Thanks,

    Kevin

  • 0 in reply to Kevin Ginunas
    TI__Genius 15770 points

    Hi Kevin,

    1. The INA3221 internal ADC is based on the delta-sigma you can find the details on Page 19 of the datasheet. 

    2. I am not aware of other diagram but I need to confirm this with design. The designer is on meetings this afternoon and I have not been able to get a hold of him. I know you mentioned you had a call with the customer this afternoon to discuss the details but I am not familiar with compensating shifts. Please ask the customer for more time until I can discuss with design. 

    Regards,

  • 0 in reply to Mayrim Verdejo
    TI__Genius 15770 points

    Hi Kevin,

    The digital designer confirmed the device do compensating shifts. The diagrams are not in datasheet as it is TI proprietary. We are happy to debug and help customer if there is any issues with the performance of the part. 

    Regards