Measurement of relative humidity and temperature is becoming one of the most common applications for sensors as manufacturers increasingly adopt artificial intelligence (AI)-driven preventive maintenance strategies for prolonging the useful life of equipment. In IoT and smart connected devices, there is great value to be gained from continuous physical and environmental monitoring, and from uploading measurement results to preventive maintenance software hosted in the cloud.
Two of the environmental factors that most quickly damage electronic equipment are excessive humidity and extreme temperatures or temperature swings. Now both can be measured with a single chip by choosing a product from the ultra-low power Renesas HS400x family.
These relative humidity + temperature sensors are exciting interest from design engineers because of their combination of superior attributes: long-term stability, low power consumption, high accuracy and precision.
The stability is reflected in the sensors’ low drift – just 0.1% change in the relative humidity measurement output per year. Power consumption can be negligible, depending on the application requirement: for instance, average current is just 0.62 µA when measuring at a rate of 1 Hz.
Accuracy is ±1.5% for relative humidity measurements, and just ±0.2% for temperature measurements in the HS401x variants. And the precision of the HS400x sensors is configurable to fit the needs of the application: at 8-bit resolution, the sensor’s power consumption is lower and response time is faster, while at 14-bit resolution, these Renesas sensors can register very small changes of as little as 0.01% relative humidity.
While the HS400x devices come in a standard package with open air inlet, the HS401x devices feature a hydrophobic membrane, making them dust-resistant and waterproof with an IP67 rating.
The easiest way to evaluate the performance of these sensor families is with a Renesas evaluation board, the HS4000-EVK. The hardware allows the user to perform data logging, and it communicates through a standard USB interface with the user’s computer. Using the Renesas Environmental Sensing-Eval software for PCs, engineers can view measurements in real time, adjust the resolution of the sensor, configure measurement parameters, and download previously logged measurements.