The HDC302x includes an integrated heater with enough current draw (up to 45 mA) to enable operation in condensing environments. The heater protects the humidity sensor area by preventing condensation as well as removing condensate. Enabling and disabling of the heater is documented in Table 8-3 and illustrated in Figure 8-35 and Figure 8-36.
The heater is expected to impact the temperature measurement result and the relative humidity measurement result. An IC-based humidity sensor uses the die temperature as an estimate for the ambient temperature. Use of the heater will increase the die temperature up to 60°C above ambient temperature. Therefore, accurate measurement results of ambient temperature and relative humidity are not possible when the heater is in operation.
As long as condensate is present on the RH sensor, the measurement reading will continue to be > 99%. Continue enabling the heater until the RH measurement reading falls to below 80%. In most cases, 2-3 minutes of heater enable time is sufficient. It is best practice to ensure that the ambient temperature is higher than the dew point temperature.
It is important to recognize that the integrated heater will evaporate condensate that forms on top of the humidity sensor, but does not remove any dissolved contaminants. This contaminant residue, if present, may impact the accuracy of the humidity sensor.