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ADS1261: Current source and measurement not working with internal reference enabled

Kupe Kriszti
Prodigy 100 points
Part Number: ADS1261
Other Parts Discussed in Thread: ADS1263

Tool/software:

In a new design, ADS1261 is used to measure 2-wire PT1000 temperature and pressure sensors. For both the internal current source is used. 

According to the datasheet, it is necessary to enable the internal reference (REFENB) to enable the current sources. When the internal reference is enabled the measurements are not working, neither the current sources are active.

If REFENB is disabled the measurements are working but of course, with wrong values as the current source is not applied.

The measurements are started by SPI command and set to continuous mode.

I worked before with ADS1263 for pressure measurement with a similar setup and there were no issues.

Can you please check what settings should also be set to start the current sources with the measurement?

  • 0
    TI__Mastermind 37795 points

    Hi Kupe,

    Welcome to the E2E forum.

    When you said "When the internal reference is enabled the measurements are not working", were you saying the RTD (PT1000) measurement is not working? Can you please clarify "neither the current sources are active"? When the internal reference is enable, you can still use the IDACs on the ADCs.

    When you said "If REFENB is disabled the measurements are working but of course, with wrong values as the current source is not applied.", I believe this is RTD measurement, . definitely the internal reference should be enabled for sensor excitation current source operation.

    BR,

    Dale

  • 0 in reply to Dale Li
    Prodigy 100 points

    Hello, the issue was with the analog power supply, as it was under 4.75V when the current source was activated, and the ADC conversions were not working.

    Now everything is functional.

    Thank you for the support!