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ADS127L01: ADS127L01 - daisy-chain drdy syncronicity lost

Marco Bevilacqua
Prodigy 110 points

Part Number: ADS127L01

Hello,

I am using 8 ADS127L01 configured in SPI daisy-chain mode sharing the same master clock, each one of them isolated through a barrier. I'm facing this problem: in the certification lab after applying big noise to the circuits the adcs loose their syncronicity. 

Before applying these noise all the 8 drdy are syncronized, after applying the noise they loose their syncronicity and sometimes I read fake data because I only monitor the the first DRDy of the chain.

Is there a possibility to syncronize every reading avoiding the reset of the digital filter and consequently its delay?

And eventually with the frame-sync slave interface what could be the situation?

Thanks

Best Regards

  • 0
    TI__Mastermind 49230 points

    Hello Marco,

    There are no synchronization options that do not require a reset of the digital filters, and the delay that this adds.  Both frame-sync and SPI daisy chain modes require a device synchronization per section 9.1.2.3 in the datasheet.

    When the devices become un-synchronized, how many CLK periods are the /DRDY signals off between devices?  If just a few CLK periods, you could add some delay after the /DRDY has toggled before transferring the data, allowing the other devices that are off by a few clock cycles to 'catch up'.  If the devices are off by as much as 1/2 of an output data cycle period, then this approach would not work.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    TI__Mastermind 49230 points

    Hello Marco,

    I have not heard back from you in some time.  I hope you were able to find a solution.

    I am going to close this post, but if you have any more questions, please feel free to start a new e2e thread.

    Thank you,

    Keith