• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 225 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.

ADS131M02: If the ADS131M02 SPI signal have the internal pull in or pull down resistance?

Kevin Zeng
Intellectual 1020 points
Part Number: ADS131M02
Other Parts Discussed in Thread: ADS131M04EVM, ADS131M04, ADS131M06

Hi Team,

I want to confirm that If the ADS131M02 SPI signal have the internal pull in or pull down resistance? 

And If have no resistance in the internal, when I use it communicate with MCU, should design the res in the MCU side?

Could you give me recommend for the schematic deisgn about ADS131M02 and MCU SPI connect? Thanks. 

  • +1
    TI__Mastermind 18900 points

    Hi Kevin,

    This is from the ADS131M04EVM (same family so its applicable).

    None of the pins have passive pullups or pulldowns on the pin. As a result, the MCU side should do the heavy lifting for SPI. Our only recommendations are to put pull ups on CS and SYNC/RESET near the ADS131M0x. DOUT will go to HI-Z as an output, logic high, and logic low. DRDY can be configured for a Logic low or high impedance (which would require pullups) through DRDY_HIZ. DIN is an input so that'll configured on the MCU side. That should be all of them!

    Best,

    -Cole

  • 0 in reply to Cole Macias
    TI__Intellectual 1020 points

    Hi Cole,

    Thanks for technical support~

    I want to confirm that whether the ADC internal reference voltage can be change?

    Customer want to reduce ADC internal reference voltage for improving the ADC resolution.

    Best,

    -Kevin

  • 0 in reply to Kevin Zeng
    TI__Mastermind 18900 points

    Hi Kevin,

    For the ADS131M04 (and below in channel count), the 1.2V reference integrated reference has no option for an external reference.

    For the ADS131M06 (and higher channel count) there is an option to feed an external reference. That being said, the voltage reference is very tight and can effectively only be around 1.25V, so they won't be able to reduce the reference voltage significantly. See the excerpt from the datasheet below:

    Kevin Zeng said:
    Customer want to reduce ADC internal reference voltage for improving the ADC resolution.

    I'm not really sure what this means, assume they mean change the LSB size? The resolution of the ADC is fixed, and thermal noise will be the dominant source of error. I would be very surprised that changing the LSB size compared to the noise spec will actually result in any actual increase in accuracy.

    See the noise table and effective resolution as a result of various gain and data-rates and its effect on resolution.

    Best,

    -Cole