Tiny Humidity Sensor Also Measures Temperature

Würth Elektronik, a leading electronics manufacturer, has recently made a significant advancement in sensor technology by shrinking a humidity sensor into a tiny 1.5 x 1.5 x 0.5mm 5pad DFN package. This breakthrough, known as the 2525020210002, offers remarkable capabilities in a compact size.

The 2525020210002 humidity sensor is designed to work over a wide range of relative humidity, from 0% to 100%. It provides accurate readings, typically within ±1.8%RH (±3.5%RHmax) over the range of 20% to 80%. Additionally, the sensor includes a temperature sensor that can measure temperatures from -40°C to +125°C with high precision. It offers an accuracy of ±0.2°C across 0 to 60°C and ±0.6°C over its full range.

One of the remarkable features of this sensor is its ability to operate at different repeatability levels. Regardless of the actual error, the sensor can be set to high (±0.08%RH ±0.04°C), medium (±0.15% ±0.07°C), or low (±0.25% ±0.1°C) repeatability modes. This flexibility allows users to choose the level of accuracy required for their specific applications.

The power supply for the sensor can vary between 1.08V and 3.6V, depending on the repeatability mode selected. The sensor consumes a low amount of power, drawing 2.2uA, 1.2uA, or 0.4uA, respectively. During reading, the power consumption increases to typically 320uA (with a maximum of 500uA). In idle mode, the sensor consumes only 50uA, and it has a shut-down mode with a power consumption as low as 80nA.

In situations where the sensor surface is covered in condensed water, the 2525020210002 sensor includes an on-board heater. The heater can be activated at various power levels and for different durations, with a maximum power of 200mW for 1 second. This feature ensures accurate readings even in challenging environmental conditions.

The sensor package includes two pads for communication via an I2C bus, while the fifth pad can be used to modify the thermal behavior of the sensor. When mounting the device, it is recommended to leave gaps in copper planes around it to reduce the effects of heat traveling through the PCB, although this may slightly impact noise performance.

It is important to note that the humidity sensor is not a typical electronic component. The sensing element is made of polymer, and long-term exposure to humidity and temperature outside the normal range (20 to 60%RH and 10 to 50°C, respectively) may affect the sensor's accuracy. To recalibrate the sensor, it can be baked at 100 to 110°C with 5%RH for 24 hours, followed by re-hydration at 20 to 30°C with 80%RH for 48 hours.

For developers and enthusiasts, a development board compatible with AdaFruit's FeatherWing standard is available for the 2525020210002 sensor. This board simplifies the integration of the sensor into various projects and provides additional functionalities.

In conclusion, Würth Elektronik's shrinking humidity sensor, the 2525020210002, is a remarkable achievement in sensor technology. Its compact size, high accuracy, and flexible repeatability levels make it an ideal choice for a wide range of applications. With its on-board heater and communication capabilities, this sensor offers advanced features that ensure reliable and precise measurements in challenging environments.