The on-chip heater in the HDC3120 can help remove condensation and accelerate drying in humid environments. However, to provide best performance and long-term reliability, the following precautions and best practices must be followed:

• Sensor Measurements During Heating:

  When the heater is enabled:

  • Temperature readings reflect the die’s internal temperature, not ambient.

  • Humidity readings appears artificially low due to localized heating.

  These values are not valid for ambient sensing. After turning the heater off, sensor temperature and RH can take up to 30 seconds or more to return to equilibrium. RH readings can stabilize even more slowly. Wait for readings to settle before relying on post-heating measurements.

• Power Supply Considerations:

  The heater increases the current draw of the device significantly:

  • Typical heater current ranges from 10–30mA, depending on V_DD.

  • Verify that your power supply and bypass capacitors can handle this surge without voltage droop. Sudden supply drops can trigger sensor resets or interfere with nearby circuitry.

  • A local decoupling capacitor (e.g., 0.1μF + 1μF ceramic) is strongly recommended.

• Condensation and Residue Risk:

  The heater evaporates water, but any dissolved minerals or contaminants in that water remains as solid residue on the sensor surface. Over time, this can degrade accuracy or slow response time.

  • The heater cannot remove non-volatile residues.

  • In environments prone to condensation or splashes, consider using a protective membrane to reduce contamination risks.

  • For heavily contaminated units, manual cleaning or sensor replacement can be necessary.

• Heater Duty Cycle and Sensor Aging:

  Frequent or prolonged heater usage can accelerate long-term aging of the humidity sensor:

  • Occasional, condition-based use is recommended.

  • Avoid running the heater continuously or at high duty cycles unless absolutely necessary.

  • For best results, activate the heater only when condensation is detected or anticipated.

Texas Instruments has qualified the HDC3120 for typical heater use. However, excessive heater activation can lead to gradual performance shifts over time. For advanced applications needing precise control and feedback, consider the digital HDC3020 device.