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HDC2022: Heater Operation

user6246822
Prodigy 75 points
Part Number: HDC2022

Hi Team,

Our product is the temperature/humidity meter for industrial use. We are facing the serious problem with the humidity drift of the HDC2022 in high humidity environment. When the HDC2022 reaches more than 80% humidity, the humidity offset increases. I know that heating operation is effective for these problems, but I don't know exactly how long I should heat it. Please let us know what you think.

  • 0
    TI__Mastermind 28070 points

    Hi User6246822,

    How much of an offset are you seeing?

    The heater may or may not be able to correct this. If the offset is from prolonged exposure above 60C and 80% humidity then it is not likely that the heater would be enough. If you want to test this, you can put the boards into an oven and bake them at 100C for 12-24 hours. Then allow the boards to rest at the datasheet recommended conditions (roughly 25C and above 60%RH to 75%RH) for another 12-24 hours.

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Prodigy 75 points

    HI Brandon,

    Thank you for your kindly support.

    Our HDC2022 is calibrated with 25C/80% environment for 1.5hour x 4 times in our application. Then 2-5% humidity offset may occur. We will change the calibration parameter to lower humidity condition.

    Does it matter if it's over 60C and over 80% at the same time? Our equipment may be used in humid environments above 80%, but rarely above 60 degrees at the same time.

    I have some other questions.

      Does the heater operation affect the life of the HDC2022?

      How long should the heater be turned on to eliminate the humidity offset?

      If you have application note about heater operation , please let me know.

      Is it possible for the offset value to get larger and larger as time progresses?

    Best Regards,

    Koji Arii

  • 0 in reply to user6246822
    TI__Mastermind 28070 points

    Hi Koji,

    user6246822 said:
    Does it matter if it's over 60C and over 80% at the same time? Our equipment may be used in humid environments above 80%, but rarely above 60 degrees at the same time.

    Above 60C and 80% RH is worse than just above 80%RH. This condition can cause accelerated aging of the polymer, which is not reversible using the heater. Chemical contamination can also cause irreversible offset in the relative humidity reading, we sometimes see this when cleaning is performed around the sensor. 

    user6246822 said:
    Does the heater operation affect the life of the HDC2022?

    Running the heater infrequently and for short periods (a few minutes at a time) will not affect the lifetime of the HDC2022. If the heater was regularly run for hours or days that would affect the lifetime of the HDC2022. Roughly 15 minutes of heater on time for every two weeks of operation is a safe amount. 

    user6246822 said:
    How long should the heater be turned on to eliminate the humidity offset?

    Some of our testing has shown that the HDC2x family of devices can recover from water droplets within 3-5 minutes of heater run time, but this if triggered immediately after the condensation is seen. If you wanted to try and run the heater one time for several hours to try and bake out any condensate on the polymer that may work, but it is not guaranteed, and it is not recommended that you do this often.

    user6246822 said:
    Is it possible for the offset value to get larger and larger as time progresses?

    If the HDC device is continuously exposed to high RH and temperature conditions then it can continue to drift over time. We would typically expect a drift of only around 0.25% RH/year under normal operating conditions. 

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Prodigy 75 points

    Hi Brandon,

    Thank you for your continuous support.

    Our equipment is often left outdoors for long time. In that case, it is necessary to automatically operate the heater when an offset occurs in the humidity.
    If you have a recommended heating sequence, please let me know.
    And when will the measurement be possible after heating?

    Best Regards,

    Koji Arii

  • 0 in reply to user6246822
    TI__Mastermind 28070 points

    Hi Koji,

    The amount of time that the device will take to return to normal after the heater is run is dependent on the amount of time that the heater was running and the layout surrounding the sensor. We unfortunately do not have enough data to provide a method for using the heater that would remove condensation successfully and completely in all cases.

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Prodigy 75 points

    Hi Brandon,

    I've understood. I will consider the heating sequence according to useful information from you. Thank you!

    Best Regards,

    Koji Arii