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HDC3022: HDC3022 temperature accuracy issue

Peter Tseng
Genius 5930 points
Part Number: HDC3022

Hi Team,

My customer tested HDC3022 with a standard meter and got some data.

As the result, the temperature had vary difference compared with the standard meter.

The red curve of below chart is standard value and the gray curve is HDC3022.

Also attached the log file and customer PCBA and layout file.

The battery is absent and powered by a power supply while testing.

20231221 data_log_1_.xlsx

ST2-0.1 PCB Layout.pdf 

Please help to check and give me your comments about it.

Thanks.

  • 0
    TI__Expert 3700 points

    Hello Peter Tseng,

    Thank you for your patience during the US holidays and for reaching out to us. From the layout you’ve shared, it seems you’re trying to measure ambient temperature. The difference you’re observing could be due to test setup, for example, a temperature gradient/difference in the test chamber. Could you provide more details about your test setup?

    As for the HDC3022 device, does the temperature difference remain consistent across different boards, or is it specific to a specific HDC3022? Can you confirm whether there have been any other devices tested with the same setup where the difference in temperature isn't observed?

    Your feedback will help us suggest the best next steps.

    Best Regards,
    Victor Salomon

  • 0 in reply to Victor Salomon
    Genius 5930 points

    Hi Team,

    After checking, the issue was impacted with GPS and LoRA modules that are the heat sources.

    Customer use fly wire to separate HDC and them and the accuracy error became small.

     

    Customer will modify the layout to try to isolate them with HDC3022.

    Another question is, according to the layout example in the datasheet, the thermal pad of IC can connect to GND or keep floating.

     

    What is your suggestion for it? floating or connecting to GND. My customer application is to sense ambient temp. and humidity.

    Thanks.

  • 0 in reply to Peter Tseng
    TI__Expert 6735 points

    Hi Peter,

    Glad to hear the temperature accuracy issue could be resolved. We recommend soldering the thermal pad of the HDC3022, however the effects of this are marginal so if the customer strongly prefers to not solder it, that is OK. Using the circular cutout in the layout image you shared will provide the necessary thermal isolation from board heat sources.

    Thanks

    -Alex Thompson

  • 0 in reply to Alex Thompson
    Genius 5930 points

    Hi Alex,

    Thanks for your reply!

    One more question is, the customer wants to know the difference between trigger-on mode and auto measurement mode?

    for example, the auto measurement mode is sampling 10 times per second, will the output be the average value of these 10 values

    or something like that.

    Thanks. 

  • 0 in reply to Peter Tseng
    TI__Expert 6735 points

    Hi Peter,

    The auto measurement mode wont do any averaging like that for you, it will just perform a temperature and humidity conversion at the specified rate. So by choosing a faster sampling rate, the user can just read a temp/RH result that many times per second. If averaging is desired, the user can collect multiple samples and perform the averaging with the controller program. Trigger on demand mode just performs a single conversion when the trigger on demand command is sent. 

    Thanks

    -Alex Thompson