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ADS1261EVM: ADS1261EVM

vadim piskun
Expert 2230 points
Part Number: ADS1261EVM
Other Parts Discussed in Thread: ADS124S08EVM, , ADS1261, ADS124S08

Hi,

ADS124S08EVM board is meant for RTD temperature measurements and Figure 15. Simplified 2-Wire RTD Input Diagram in this manual shows it

https://www.ti.com/lit/ug/sbau272a/sbau272a.pdf?ts=1702411511846&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FADS124S08EVM

Can I use ADS1261EVM in a similar manner without any external components?

www.ti.com/.../sbau293a.pdf

Is there an apps note showing it?

Thanks vadim

  • 0
    TI__Mastermind 45731 points

    Hi vadim piskun,

    The ADS1261EVM does not natively support an RTD configuration, so you will have to add some components.

    There is an option for a reference resistor on both the REF1 (R13) and REF0 (R20) inputs, as shown in the image below. If you are using a low-side reference resistor, ensure that the negative channel is grounded (either REFN0 or REFN1).

    Then you can use any applicable IDAC output to bias the RTD. And of course, the RTD must be supplied externally by you

    Refer to our RTD design guide for more information: https://www.ti.com/lit/an/sbaa275a/sbaa275a.pdf?ts=1702414806076&ref_url=https%253A%252F%252Fwww.google.com%252F

    -Bryan

  • 0 in reply to Bryan Lizon86
    Expert 2230 points

    Thanks Bryan,

    I will try first ADS1x4S08 first. There is detailed description in the user guide how to connect  3 wire PT100 sensor, but not much regarding software configuration. Is there a script where i can control current and PT resistance?

    thanks vadim

  • 0 in reply to vadim piskun
    Expert 2230 points

    Actually i found one 3 wire rtd

  • 0 in reply to vadim piskun
    TI__Mastermind 45731 points

    Hi vadim piskun,

    I am not sure what you mean by "control... PT resistance". Neither the ADS124S08 or ADS1261 EVMs come with an RTD, this always needs to be applied externally. The only real difference between these EVMs is that the ADS124S08 has a reference resistor installed, while the ADS1261 EVM has a space for a resistor, but you would need to populate it yourself.

    For both EVMs, the reference resistor can always be installed externally using the terminal blocks

    -Bryan

  • 0 in reply to Bryan Lizon86
    Expert 2230 points

    Hi Bryan

    I meant replacing PT100 with PT1000

    thanks vadim

  • +1 in reply to vadim piskun
    TI__Mastermind 45731 points

    Hi vadim piskun,

    Note that the default reference resistor on the ADS124S08EVM is a 1kohm resistor, so you will not be able to measure any RTD resistances greater than this value. This is important if you choose to use a Pt1000, whose nominal impedance is 1kohm at 0°C

    You would need to replace the reference resistor with a larger value if you intend to measure a Pt1000, unless you only want to measure negative temperatures

    -Bryan