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ADS124S08: DRIFT ON TEMPERATURES ABOVE 80C

Sebastian Higuita
Prodigy 40 points
Part Number: ADS124S08


Tool/software:

Hi,

I am using the following configuration and setup. All readings start to drift significantly around 80 C to 125 C. Any idea why is that?

INPMUX_ADDR_MASK, 0x23 ); 

PGA_ADDR_MASK, 0x40); 

DATARATE_ADDR_MASK, 0x02); 

REF_ADDR_MASK, 0x02 ); 

IDACMAG_ADDR_MASK, 0x04);

IDACMUX_ADDR_MASK, 0xF0);

SYS_ADDR_MASK, 0x11

  • 0
    TI__Guru 53736 points

    Hi Sebastian Higuita,

    This sounds like temperature drift, which is not necessarily linear.

    Can you provide more detail on how the readings drift?

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 40 points

    Hi Bryan,

    Thanks for your reply.

    Before I implemented the ADS124S08 into my application, I carried out few tests using the ADS124S08 EVM Board.

    Some Changes were made.

    R68 5000K

    R70 1500K

    PT1000

    Temperature readings after conversion using the EVM

    Max drift 0.23 ohms.

    Now, with the ADS124S08 in my board same PT1000

    Max drift 5.3 ohms

    Thanks for you help.

    Sebastian

  • 0 in reply to Sebastian Higuita
    TI__Guru 53736 points

    Hi Sebastian Higuita,

    This definitely looks like a temperature dependent gain error i.e. drift, because the error from 23C to 125C is approximately 0.2% for all the combinations you are showing in your table

    Have you tried measuring the resistance of the reference resistor to see how much it changes as you increase the temperature?

    Have you tried calibrating the sensor or system (or both) to see if the error changes?

    Are there any other differences between your board and the EVM that could cause drift errors?

    -Bryan