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HDC2010: offset drift

Eric Dj
Expert 4130 points
Part Number: HDC2010
Other Parts Discussed in Thread: HDC2080, HDC1010, HDC1080

Team, I have received the question below from my customer. Can you help me to address it?

rgds, Eric

We have a problem with a humidity sensor (HDC2010) that has been selected on a design to track the humidity level in a "dry cavity" type meter housing, i.e. a hermetic housing with desiccant, which leads to a humidity level close to zero. It turns out that our tests show abnormally high results of more than 20% RH with a varying offset, which first led us to believe that our boxes had leaks, but after analysis, it is the sensor measurement that is wrong.

If you read the datasheet carefully, you will find the explanation:

We had not paid attention to this point before because the sensor is well suited for a range of 20% to 80%.

Is our analysis the right one, is it the fact that we are always below 20% HR that shifts our measurement? If so, do you have another sensor in your range that is suitable for these conditions (low permanent humidity)?

  • 0
    TI__Expert 5695 points
    Hi Eric,
    During the IC validation phase we do a Relative Humidity (RH) sweep from 20%RH to 75% in humidity chambers. We report our accuracy (as you know) from 20% to 80% as indicated in the data sheet.
    In reality our chambers cannot go lower than RH 20% . The sensor should work from 0% to 20%RH but we don’t have a way to estimate the accuracy at those levels. We don't have any humidity sensor that has a spec for RH lower than 20%.

    If the accuracy is quite off it's possible that the sensor was contaminated. One way to verify this will be measuring RH inside the supported range (e.g. at 40%). In order to be familiar with the guidelines to avoid this possible contamination please refer to the following docs:

    I. HDC 2010 Data Sheet – Section 10.1.1 Guidelines for HDC2010 Storage and PCB Assembly. This section briefly discuss key topics on soldering reflow, rework, simultaneous exposure to high temp & high humidity, Bake/Re-Hydration Procedure.
    II. HDC 2080 Data Sheet – Section 11.1.1 Guidelines for HDC2080 Storage and PCB Assembly. This section briefly discuss key topics on soldering reflow, rework, simultaneous exposure to high temp & high humidity, Bake/Re-Hydration Procedure.
    III. Humidity Sensor: Storage and Handling Guidelines. This application note describes storage and handling guidelines of humidity sensors, including the HDC1010, HDC1080, and HDC20X0.

    Regards,
    Jose