SNAU265C june   2021  – july 2023 HDC3020 , HDC3020-Q1 , HDC3021 , HDC3021-Q1 , HDC3022 , HDC3022-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1HDC302x Devices
    1. 1.1 HDC3020 in WSON
    2. 1.2 HDC3021 in WSON
    3. 1.3 HDC3022 in WSON
  5. 2Storage and Handling Guidelines
    1. 2.1 Exposure to Contaminants
    2. 2.2 Chemical Analysis
      1. 2.2.1 Saturation and Recovery Tests
      2. 2.2.2 Long-Term Exposure
    3. 2.3 Packaging and Storing
      1. 2.3.1 Assembly
      2. 2.3.2 Application in Extreme Environment
  6. 3Programming the HDC3020
    1. 3.1 Trigger-On Demand
    2. 3.2 Auto Measurement
    3. 3.3 Programming the CRC
      1. 3.3.1 CRC C Code
    4. 3.4 Condensation Removal
    5. 3.5 Offset Error Correction
      1. 3.5.1 Offset Error Correction Example With a Fingerboard
  7. 4References
  8. 5Revision History

3.4 Condensation Removal

Certain environments can force the temperature to drop below the dew point. During such an event, condensation can occur on the device. The sensor opening will be blocked and this can impact accurate sensor readings. In such situations, the integrated heater on the HDC3020 can be beneficial to remove any condensation and can continue reading error free measurements.

Note:

The HDC3020 should only be used in a non-condensing environment. The recommended humidity operating range is 10 to 90% RH (non-condensing) over –20°C to 70°C. Prolonged operation beyond these ranges may shift the sensor reading with a slow recovery time. Excess condensation could degrade sensor performance and might make it harder to recover.

The HDC3 comes with a configurable heater to allow customers to use the heater based on their application and the amount of power needed to evaporate the condensation. The highest power (lowest resistance) offered on this device is 35.92 Ω and the lowest power (highest resistance) is 1996 Ω. This setting can be configured as needed but the recommended resistances are outlined in Table 3-2.

The recommended operating condition for the heater can be set between 1.62 V to 5.5 V. The condensation removal is layout-dependent as some layouts would need more power or more time to evaporate the moisture. The recommended layout can be found in the Layout Example section of the data sheet. Users can configure a setting between 25% and 100% and characterize a setting based on the layout and application. Users must note that they need to calculate and write the CRC to the device based on the heater configuration.

Calculating the dew point (DP) from the temperature and humidity measurements can be important when it comes to this feature. If the temperature drops below the DP, the device can be placed in an environment where the temperature gets above the DP and the heater can be enabled. The user can also leverage the ALERT output, which is triggered when the part crosses preset temp and %RH levels. The timing of this process can take a couple of minutes, sometimes even five minutes until the device can read the temperature and humidity accurately. When the %RH reading goes to zero % (or near it), the heater can be subsequently turned off to allow the device to cool down. Cooling of the device can take several minutes, but the temperature measurement will continue to run to ensure the device goes back to normal operating condition before restarting the device for normal service.

Refer to the flowchart in Figure 3-3 to configure and enable the heater.

GUID-20220713-SS0I-XJR3-XWJS-R8ZVCMXGLJT9-low.svgFigure 3-3 Flowchart for Condensation Removal.

The integrated heater evaporates moisture that forms on top of the humidity sensor, but does not remove any contaminants. Any contaminant residue, if present, may impact the accuracy of the humidity sensor and can cause drift. If the device experiences drift due to contamination or precipitation, refer to the Offset Error Correction section.