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ADS1220: DOUT/DRDY behavior

Genius 15690 points
Part Number: ADS1220

Hello,

 

My customer would like to understand DOUT/DRDY behavior with DRDYM=1 and single-shot mode.

Unfortunately, there is no figure to explain it in the datasheet.

 

1.

When the host sends START/SYNC command, does DOUT/DRDY signal always go to high along with DRDY pin?

 

2.

The datasheet explains that sending 8 additional SCLK with DIN=0 after reading conversion result makes DOUT/DRDY goes to high.

Is this behavior the same when reading the data by RDATA command?

 

Regards,

Oba

  • Oba,

    I will provide a preliminary answer to your questions.  To confirm that my preliminary response is correct, I will measure this in the lab.  However, this will require some customer software and hardware, so it will take a few days.

    1. I believe that the DOUT/DRDY signal should track DRDY after the START/SYNC command.  You can see that it does in continuous conversion mode (FIG 62).  I agree with you that there should be a figure after figure 63 for single shot mode with DRDYM = 1.  Will measure to confirm.

    2. I believe that the 8 additional clocks on the RDATA command should make DRDY go high as it does with the inherent read.  I need to confirm this.  However, I would expect that you could read as shown in figure 63 (modified so that the DRDYM = 1).

    Sorry I don't have the complete answer now.  This will take a few days.

  • Oba,

    A short update:

    I have devices on order and will setup our debug system when they arrive.  I will be able to confirm the operation then.

    Art 

  • Thanks for your update.

    Regards,
    Oba

  • Hello,

    Do you have any update?

    Regards,
    Oba

  • Oba,

    Sorry for the delay.  I had to order samples.  They are scheduled to arrive today, so I will hope to have an answer for you soon.

    Art

  • Oba,

    I have confirmed that the preliminary answers were correct by measuring the device.  See attached presentation.  Sorry for the delay; I had to get hardware and software to verify.

    1. DOUT/DRDY will always track DRDY when DRDYM = 1 assuming the extra 8 clock pulses are provided after the read.
    2. The 8 clock pulses allow DOUT/DRDY to track DRDY.
    3. The behavior works the same for the RDATA command. The RDATA command is followed by a 24 bit read, then 8 extra clocks allow DOUT/DRDY to track DRDY.
    4. The cases above are documented in the attached power point. I can try additional experimentes using this setup as needed.

    Best regards,

    Art

    ADS1220-SingleShot-1-31-2022.pdf

  • Hello Art,

    Thank you very much for the test result.

    Regards,
    Oba