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ADC12DJ3200: Background calibration period

Steve Widener
Genius 11010 points
Part Number: ADC12DJ3200

Do we have guidance on the period of background calibration?

Are there any flags set that could be used to indicate the transitions?

  • 0
    TI__Mastermind 20541 points

    Hi Steve,

    The ADC core transition(swapping) during background calibration operation is transparent to the user. The data coming out of the ADC is uninterpreted and the user see a constant stream of data. 

    Regards,

    Neeraj 

  • 0 in reply to Neeraj Gill
    TI__Genius 11010 points

    Thanks Neeraj!

    Let's dig a little deep on this one - I see that in Figures 61 and 63 of the datasheet, there is a noticeable glitch in the signal as seen at the ADC output due to background core transitions. Do you agree?

    If I'm interpreting this correctly, this would affect bit errors and it may be a concern in some high reliability systems

    So if we could have some indication of the period (either time or # of cycles) for the background cal ADC swap along with any guidance regarding an indicator that the switch occurs, that would really help out.

    Best Regards,


    Steve

  • 0 in reply to Steve Widener
    TI__Mastermind 20541 points

    Hi Steve,

    The customer should be able use the following sequence to make sure they are capturing the clean output from the ADC without the glitch.

    Make sure background calibration in is running. Write 0x00 to 0x6C (cal_soft_trig) this will stop the back ground calibration. To check if background calibration has been stopped check cal_stopped bit.This bit will retun a 1 when background calibration has successfully stopped at the request phase.

    The capture should be without any glitch when background cal_stopped is 1.

    You can again start the core swapping( background calibration) by setting the 0x6C(cal_soft_trig) to the value of 0x01.

    Regards,
    Neeraj

  • 0 in reply to Neeraj Gill
    TI__Genius 11010 points

    Thanks Neeraj!

    Is there any signal that can be used to indicate that a background cal has occurred that can be correlated to the incoming data?

    What is the approximate frequency of the background cal process?


    Steve

  • 0 in reply to Steve Widener
    TI__Prodigy 671 points

    Hi Steve, you may want to look into the Low-Power Background Calibration mode which offers more controls than free-running BG calibration.

    Regards,

    Kyle