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Original question:

Issues using ADS1118 and 3 wire RTD, PT1000, in wheatstone configuration

ADS1118: ADS1118 RTD Interface

Ray Vincent Aranzaso
Mastermind 18180 points
Part Number: ADS1118
Other Parts Discussed in Thread: ADS1120

Hi,

Good Day. I have a customer who has a query with regards of E2E Forum thread.

Please see below for his query. Thank you very much.

In the below thread, there is a recommended circuit for 3 wire RTD interface with ADS1118.

e2e.ti.com/.../issues-using-ads1118-and-3-wire-rtd-pt1000-in-wheatstone-configuration

Any recommendations for R and Rref resistor values for PT100 3 wire RTD interface?

Best Regards,

Ray Vincent

  • 0
    TI__Guru 54166 points

    Hi Ray,

    Typically you would use an ADC with differential reference inputs and integrated current sources for an RTD measurement. The ADS1118 has neither of these components, so it is not an ideal ADC for an RTD application.

    Instead I would suggest the ADS1120, another 16-bit delta-sigma ADC that includes both of these features. The ADS1120 datasheet specifically includes a section on a 3-wire RTD application (9.2.2).

    Also, we have an excellent piece of collateral that includes lots of important information about RTD measurement circuits. Please have your customer review this information as it will help answer many of their questions: https://www.ti.com/lit/an/sbaa275/sbaa275.pdf

    -Bryan