HC109 Humidity / Temperture Sensor The HC109 is designed to meet the needs of mass production automated assembly lines at a competitive price. The HC109 humidity sensors are positioned on the PCB at the same time as other SMD components and soldered using the reflow soldering method. The HC109 humidity sensor exhibits high reproducibility of sensor data and excellent linearity over the entire humidity range. The temperature dependence is also highly reproducible and allows software temperature compensation. This means a high accuracy over a wide temperature range, which is important e.g., for the calculation of the dew point temperature. Typical Applications Features Automotive SMD mounting Home appliances High reproducibility Industrial applications Very good long term stability Small-size construction Technical Data Nominal capacitance C0 (at 30 °C / 86 °f) Temperature dependency Working range Humidity Temperature Linearity error (0...98 %RH) Long term stability at 20-30 °C (68-86 °F) / 20-80 %RH Loss tangent, typ. Maximum supply voltage (no DC voltage) Maximum DC voltage Operating frequency 1) More details see “Characteristics” section 2) In environments with high concentrations of volatile organic compounds, the value may be higher. Characteristics The average increase of capacitance over the working range is 27.5 pF (HC109). For the range of 0...98% RH linear approximation is possible, errors will be lower than < ±1.5 %RH. The sensor characteristic is determined by the following linear formula: with HC0 = 3 420 ± 191 ppm / %RH HC0 ... Humidity Coefficient HC109 v1.6 / Modification rights reserved

For high accuracy requirements, the sensitivity is determined by the following polynomial: C(RH) = C0 * [1 + HC0 * RH + K(RH)] The working range of the humidity sensors HC109 is shown with regard to the humidity / temperature limits. Although the sensors would not fail beyond the limits, the specification is guaranteed only within the working range. In applications with high humidity at high temperatures the time factor shall be considered. To allow full access of the air, the humidity sensor should be positioned over an opening in the printed circuit board (PCB). False readings because of humidity...