The HDC3120 includes an integrated on-chip heater designed to elevate the temperature sensor above ambient. This function serves multiple purposes: the function accelerates the drying of the humidity-sensing element and facilitates the outgassing of absorbed contaminants from the sensing polymer. By raising the sensor junction temperature, the heater can prevent or mitigate conditions that negatively impact sensor performance and long-term stability.

Key applications of the on-chip heater include:

• Condensation Prevention: Heating the sensor when ambient conditions approach the dew point can prevent condensation from forming on the sensor surface. This is especially critical when the sensor is not enclosed in a protective housing. Moisture ingress under the sensor package can lead to short circuits between exposed sensor pins, potentially causing permanent damage to the device or the user’s system.

• High-Humidity Stability: In continuously high-humidity environments, periodic heating helps to evaporate residual moisture that can accumulate on the sensing element. This reduces long-term drift and maintains the accuracy of humidity measurements.

• Contaminant Bake-Out: The heater can be used for extended durations (up to several hours, depending on system constraints) to accelerate the removal of volatile organic compounds (VOCs) or other contaminants that can be absorbed by the sensing polymer. This process restores the sensor closer to the baseline behavior.

• Device Self-Test: Activating the heater can also serve as a basic functionality check. A measurable rise in temperature indicates that the sensor and heater circuitry are operational.

The on-chip heater plays a vital role in maintaining sensor performance under challenging environmental conditions by keeping the sensing element dry and uncontaminated when needed. For best performance, the heater is most effective at V_DD ≥ 2.5V, with 3.3V or higher recommended for achieving a temperature rise (ΔT) of more than 10°C.