Digital solutions for precise measurements

Temperature and relative humidity measurements are required in many different product applications, and a large number of digital sensors have been developed to meet this need. Honeywell has studied sensor digitization technology and its advantages, and through this article, we will guide you through its potential applications.

In the past, humidity/temperature sensor users had to convert analog signals into digital signals. This not only requires the addition of signal conditioning components, but also may lead to signal loss and more circuit errors. Some users also use digital sensors for applications with strict accuracy requirements and without hysteresis and temperature effects. However, the application results are not satisfactory, the sensor accuracy is lower than expected, and some require OEMs to spend extra time and cost for calibration. What's more, if the problem cannot be solved in the early stage, it will cause a worse situation and lead to system warranty issues.

Honeywell now introduces the HumidIcon digital humidity/temperature sensor: HIH-6130/6131 series. This series of sensors combines accuracy, stability, energy efficiency and digital output of humidity and temperature, making it suitable for a wide range of potential applications.

application

Potential applications for these sensors include air conditioning/air movement systems, thermal sensing, thermostats, humidifiers/dehumidifiers, and humidistats, which provide accurate relative humidity and temperature measurements to maintain ideal humidity/temperature for indoor comfort. In addition, the sensor also has low power consumption.

An example application is a heating, ventilation and air conditioning (HVAC) system for a communications cabinet that provides accurate relative humidity and temperature measurements to maintain temperature and humidity levels to ensure proper operation of the cabinet.

This series of sensors is also suitable for weather stations to help accurately and in real time monitor and report weather conditions. In the chemical industry, people use this sensor in incubators or artificial environments to support key processes and experiments and improve process efficiency; in the medical equipment industry, the sensor is used in sleep apnea machines and ventilators to perform accurate relative humidity and temperature measurements to ensure that the equipment supplies warm and humid air, enhance patient comfort and safety, and improve treatment efficiency.

In addition, this solution can also be used to measure relative humidity in compressed air pipelines to prevent condensation in the system and ensure dry compressed air is supplied in the pipeline, which is critical for process control measurements.

technology

Honeywell's sensors provide true temperature-compensated digital I2C outputs, allowing customers to remove signal conditioning components from the PCB, freeing up space and reducing costs. In addition, this simplifies integration with microprocessors, and customers no longer have to implement complex signal conditioning. Digital I2C outputs mean that this series of sensors is easy to integrate with microprocessors, and in many cases, can share the data communication bus with other sensors currently in use.

Let’s take a closer look at the benefits of these sensors: long-term (5-year) stability of 1.2% RH and accuracy of ±5% TEB over (fully compensated temperature range) 5°C to 50°C and 10% to 90% RH. TEB includes all possible sensor error sources, which effectively reduces individual sensor testing and calibration, supports system accuracy and warranty claims, helps optimize system uptime, and provides excellent sensor interchangeability, saving companies time and money.

One or two optional relative humidity level alarm outputs allow the user to monitor if relative humidity levels exceed or fall below preset values ​​for the application.

Typically, humidity sensors require a 12-hour RH rehydration process at 75% RH in a special equipment room to correct for reflow temperature deviations. HumidIcon devices only require a 5-hour rehydration process at an RH>50% environment. This long-term stability minimizes system performance failures, making the sensor maintenance-free and replacement-free during its service life, ensuring maximum continuous operation time, while also eliminating the need for regular recalibration of the sensors in use.

Additionally, the multi-layer construction of the sensing element resists most application hazards such as condensation, dust, dirt, grease and common environmental chemicals.

Another big advantage of this sensor is energy saving. The supply voltage of this series of sensors is as low as 2.3Vdc, which is fully capable of low-energy and wireless compatible applications. When powered by a battery, the sensor will enter a "sleep mode" when not measuring, consuming only 1µA of current; when working at full power, the current consumption is 650µA.

The ultra-small SOIC-8 SMD package is available in two configurations for a wide range of applications: HIH-6130 – no filter, no condensation; HIH-6131 – hydrophobic membrane filter, condensation resistant.