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ADS124S08: Inquiry on considerations for using ADC's

Bobby Kim
Prodigy 86 points
Part Number: ADS124S08
Other Parts Discussed in Thread: ADS131M04

Tool/software:

Hi, 

I am planning to develop a system the following combination for sensing,

① 3-Wire RTD(PT-100) with 6 channels(Using IDAC, 4AIN/RTD) : ADS124S08 2ea

② 4~20mA 4 channels : ADS131M04 1ea

Could you please confirm if this combination is possible? additionally, are there any specific considerations or any issues i should be aware of when implementing this IC's.

Thanks

  • 0
    TI__Mastermind 40391 points

    Hi Bobby Kim,

    The ADS124S08 will work well for measuring RTDs. We designed the ADS124S08 to measure all kinds of analog temp sensors (RTD, NTC, thermocouple, etc.). You can also reference this guide for more information about RTDs: https://www.ti.com/lit/an/sbaa275a/sbaa275a.pdf?ts=1720702089225&ref_url=https%253A%252F%252Fwww.google.com%252F

    The ADS131M04 could work for 4-20mA measurements. Keep in mind that the M04 only supports an internal reference voltage, and that voltage is 1.2V. Therefore, you will need to make sure the voltage across the shunt is <=1.2 V

    The ADS124S08 could also work for 4-20mA measurements. The ADS124S08 supports a wider reference voltage range (up to AVDD), and the internal VREF is 2.5V

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 86 points

    Thank you very much for your kind explanation. I've a some questions regarding the configuration as below,

    1. Is it possible to have multiple configurations as below picture?

    2. Can Data Ready be connected together since they are active low...?

    Thanks

  • 0 in reply to Bobby Kim
    TI__Mastermind 40391 points

    Hi Bobby Kim,

    I believe this should work, though I have never tried it. Ensure that the SCLK speed and I/O voltage you choose are supported by all ADCs.

    If you are going to synchronize the start of both ADS124S08s, and they both will have the same data rate, then you only need 1x DRDY pin to be connected from the ADS124S08. The ADS131M04 will need its own DRDY pin, since the M04 has a completely different clock and data rate compared to the S08 

    -Bryan