Humidity Sensors
Products (2)
HTS221 - Capacitive Digital Humidity & Temperature Sensor | STMicroelectronics
The STMicroelectronics HTS221 is a compact, ultra-low-power capacitive digital humidity and temperature sensor designed for a wide range of applications including IoT, wearables, and environmental monitoring. It integrates a sensing element, analog front-end, and a 16-bit ADC in a single 2.0 x 2.0 x 0.9 mm HLGA package, providing accurate relative humidity and temperature measurements with minimal power consumption. A humidity and temperature sensor is a device that measures the amount of water vapor in the air and the ambient temperature, converting these physical quantities into digital signals for processing. In the system hierarchy, the HTS221 is a MEMS sensor that falls under the category of environmental sensors, which are part of the broader sensor family used in IoT, automotive, and industrial applications. Its role is to provide real-time environmental data that enables smart systems to react to changes in humidity and temperature. Key features of the HTS221 include a relative humidity accuracy of ±3.5% RH (20-80% RH), a temperature accuracy of ±0.5 °C (15-40 °C), and a humidity resolution of 0.004% RH. The sensor operates from a 1.7V to 3.6V supply, with a typical current consumption of 2 µA at 1 Hz output data rate, making it ideal for battery-powered devices. It communicates via I2C and SPI interfaces, and includes a programmable interrupt output for threshold detection. The HTS221 uses a capacitive sensing principle, where a polymer dielectric absorbs water vapor, changing the capacitance of the sensing element. This change is converted to a digital signal by a 16-bit ADC, providing high resolution and stability. The sensor also features an embedded heater for dew point measurement and condensation prevention, enhancing its versatility in demanding environments. Typical applications include smart home thermostats, HVAC systems, weather stations, and wearable health monitors. In smart thermostats, the HTS221 provides accurate humidity and temperature data to optimize comfort and energy efficiency. In wearables, its low power consumption extends battery life while enabling continuous environmental monitoring. When designing with the HTS221, ensure proper PCB layout with a clean ground plane and adequate decoupling capacitors (100 nF) near the VDD pin. The sensor should be placed away from heat sources and direct airflow to avoid measurement errors. For best performance, follow the recommended soldering profile and reflow conditions specified in the datasheet.
HTS221TR - Capacitive Digital Humidity & Temperature Sensor | STMicroelectronics
The HTS221TR is a compact, ultra-low-power capacitive digital humidity and temperature sensor from STMicroelectronics, packaged in a 3x3x0.9 mm HLGA (HLGA-6L) package. It integrates a sensing element and a mixed-signal interface, providing calibrated digital output over an I2C or SPI interface. The sensor measures relative humidity from 0% to 100% RH with an accuracy of ±3.5% RH (20-80% RH) and temperature from -40°C to +120°C with an accuracy of ±0.5°C (15-40°C). It operates from a 1.7V to 3.6V supply, drawing only 2 µA at 1 Hz sampling rate, making it ideal for battery-powered applications. A humidity sensor is a device that measures the amount of water vapor in the air, typically expressed as relative humidity (RH). The HTS221TR is a capacitive-type sensor, where the dielectric constant of a polymer layer changes with humidity, altering the capacitance of the sensing element. This change is converted to a digital signal via an internal ADC. In the broader system hierarchy, the HTS221TR is a MEMS environmental sensor, falling under the category of sensors, specifically temperature and humidity sensors, which are essential components in IoT, smart home, and industrial monitoring systems. Key features of the HTS221TR include its factory-calibrated output, eliminating the need for user calibration, and its programmable interrupt outputs for threshold detection. The sensor supports both I2C (up to 400 kHz) and SPI (up to 10 MHz) interfaces, providing flexibility in system integration. It also features a 16-bit resolution for both humidity and temperature, with a humidity resolution of 0.004% RH and temperature resolution of 0.01°C. The device includes an embedded heater for condensation prevention, which is useful in high-humidity environments. Technically, the HTS221TR uses a MEMS capacitive sensing element with a dedicated ASIC for signal conditioning. The sensor's low power consumption (2 µA at 1 Hz) and wide supply voltage range (1.7V to 3.6V) make it suitable for portable and wearable devices. The HLGA package is designed for surface mounting, with a small footprint of 3x3 mm, enabling compact PCB designs. The sensor's response time is typically 8 seconds for humidity and 5 seconds for temperature, ensuring real-time monitoring capabilities. Typical applications include smart home climate control, where the sensor monitors indoor humidity and temperature to optimize HVAC systems; industrial environmental monitoring, where it tracks conditions in warehouses or server rooms; and wearable devices, where it measures skin humidity and ambient temperature for health tracking. The sensor's accuracy and low power make it ideal for battery-operated IoT nodes. When designing with the HTS221TR, ensure proper PCB layout to minimize the influence of heat sources on temperature readings. Place the sensor away from components that generate heat, and provide adequate ventilation for humidity sensing. The sensor's I2C address is 0x5F, and it supports multiple devices on the same bus with different addresses.