• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 45 subscribers
  • Views 56 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS131M08: Offset/Noise in measurements with the ADS131M08.

Felipe de Andrade
Prodigy 40 points
Part Number: ADS131M08

Tool/software:

Good morning, everyone!
I am using an ADS131M08 to read signals on my board, but I have been experiencing some unwanted oscillations in the collected values. After conducting some analysis, I identified that my ADC is consistently reading a voltage of 200µV on the channels, even when the inputs are completely grounded.
The circuit I am using is as follows:

In this case, I removed the capacitors in parallel with the inputs and disconnected what was coming from the rest of the circuit. Then, I interconnected my differential inputs and grounded each pair, leaving a 2.2kΩ resistor in the path. With this configuration, I am reading approximately 200µV on the channels or 1700 bits. I would like to know if this offset or oscillation is normal, as I couldn't find this information in the datasheet. The temperature is around 27 °C, and I am using an ADR127AUJZ as an external reference.

  • +1
    TI__Mastermind 39865 points

    Hi Felipe,

    Thanks for sharing your schematic and it looks good to me.

    Yes, this is the offset error as you have shorted the input for the measurement. You can see the information below, the typical value of offset error is 240uV, the 200uV you measured is close to the typical value and your measurement is reasonable. If you enable the Global-chop mode by setting the GC_EN bit in the CFG register to 1, the offset error should be reduced.

    BR,

    Dale