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ADS1261: ADS1261BQWRHMRQ1 can't write to register address 0x06 with value 0x10

Quoc Nguyen Van
Prodigy 10 points
Part Number: ADS1261

Hi all,

I'm working with ADC ADS1261 and I'm facing with the problem.

I can't write success to register at address 0x06 with value 0x10. After I trying to write 0x10 into this register to change "Internal Reference Enable", the read back value always is 0x05(default value).

But I can write success into the other registers. Except register 0x06 can't write 0x10 into it.

I had write success 0x10 into register of part ADS1261BIRHBT, but ADS1261BIRHBT is out of stock so i had change to ADS1261BQWRHMRQ1.

Please confirm with me you can write success 0x10 into register 0x06 of part ADS1261BQWRHMRQ1.

Thank you so much.

Best regards,

  • 0
    TI__Guru 52496 points

    Hi Quoc Nguyen Van,

    The ADS1261B and ADS1261B-Q1 should behave the same in terms of reading from and writing to the registers. To clarify what is going on here:

    • You install the ADS1261B
    • You write to all registers, including the REF register, and everything works as expected (the internal reference turns on)
    • On the same board, you remove the ADS1261B and install the ADS1261B-Q1
    • You write to all registers
      • Everything works as expected EXCEPT for the REF register
      • Instead, the REF register does not update and the internal reference does not turn on (you should be able to detect if the internal reference is enabled by measuring the voltage at the REFOUT pin

    Let me know if this is what is happening. If so, there is no obvious reason why this would occur, so we will have to dig in a little deeper.

    Also, I am showing a small quantity of this device currently available in the TI store, if you are interested.

    -Bryan

  • +1 in reply to Bryan Lizon86
    Prodigy 10 points

    Hi Bryan Lizon86,

    I had solved my issues. The root cause is come from inrush current when enable internal reference. When enable reference voltage the output REFOUT pinout will charge for external capacitor 10uF. It cause drop voltage of AVDD so ADS1261 is reset. That is the reason why i read register 0x06 is 0x05(default value).

    Thank for your help.

    Best regards,

  • 0 in reply to Quoc Nguyen Van
    TI__Guru 52496 points

    Hi Quoc Nguyen Van,

    Thanks for letting us know what the issue was. Would be able to share how you solved this issue? This information could be useful for other engineers who have the same or a similar issue

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 10 points

    Hi Bryan,

    I had reduce capacitor ad REFOUT pin of ADS1261 from 10uF to 1uF to resolve this problem.

    Thanks,

  • 0 in reply to Quoc Nguyen Van
    TI__Guru 52496 points

    Hi Quoc Nguyen Van,

    Great, thank you for posting this information!

    -Bryan