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Design Guide for Humidity and Temperature Sensors
A comment on how to properly design-in an SHTxx or STSxx.
SHTxx are humidity and temperature sensors of highest quality with a broad range of different features. To
take full advantage of their outstanding performance, several housing and PCB design rules need to be
considered. This document aims to provide help during the design-in phase of your product and fosters a
deeper understanding of the sensor's functionality. Please note that unbeneficial housing and/or PCB designs
may cause significant temperature and humidity deviations as well as an increased response times.
Most important Design-In Recommendations
Figure 1. A small dead volume allows for rapid
adaption to changes in the environment.
Figure 3. A large opening in the housing provides
improved air exchange and thus enhanced access
to the environment.
www.sensirion.com / D1
Figure 2. Separating a sensor compartment from
the remaining housing minimizes the influence of
entrapped air on the sensor.
Figure 4. Decoupling of the sensor from heat
sources on the PCB minimizes the influence of
internal heating on the sensor.
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Version 2 – March 2024
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Table of Contents
Related Manuals for SENSIRION SHT41
Summarization of Contents
Design Guide for Humidity and Temperature Sensors
Most Important Design-In Recommendations
Key recommendations for optimal sensor integration and performance in product design.
1 Humidity Fundamentals
Relative Humidity %RH
Explanation of relative humidity, its definition, and its significance in various environments.
Dew Point and Condensation
Details on dew point and the phenomenon of condensation and its implications.
2 Sensor Performance
Capacitive Humidity Sensing Principles
Overview of how capacitive humidity sensors operate by measuring capacitance changes.
Identifying Measurement Needs
Guidance on determining required measurement range, accuracy, and response time for applications.
System vs. Sensor Accuracy
Discussion on how overall system accuracy depends on sensor and external factors.
Representative Sampling Location
Ensuring sensor placement provides readings representative of the overall environment.
Sensor Response Time
Explanation of how quickly the sensor reacts to changes in humidity and temperature.
Effect of Condensation on Sensors
How condensed water affects Sensirion sensors, noting minimal impact within specifications.
Creep and Drift Explained
Definitions and causes of creep and drift, which affect sensor reading offsets over time.
Sensor Contamination Effects
Impact of foreign substances on sensor readings and how contamination affects accuracy.
3 Thermal Considerations
Self-Heating in Sensors
Analysis of internal heat generation within sensors and its effect on temperature readings.
Temperature Impact on Analog Sensors
How temperature influences analog sensor performance and design considerations.
Thermal Design-In Conclusion
Final recommendations for thermally isolating the sensor from the device for accurate measurements.
4 Electrical and Signal Considerations
Analog vs. Digital Sensor Outputs
Comparison of analog and digital sensor interfaces and their suitability for different applications.
Sensor Electric Specifications
Information on power supply needs, heater usage, and other electrical parameters for sensors.
ESD Protection Measures
Guidelines for protecting sensors from electrostatic discharge during handling and assembly.
I2C Communication Protocol
Factors and considerations for implementing the I2C communication interface with sensors.
5 Housing and PCB-Design Integration
Designing for Airflow
Strategies for designing device housings to ensure proper airflow around the sensor.
Minimizing Dead Volume
Techniques to reduce dead volume in housing designs for faster humidity response times.
Aperture Size Considerations
How aperture size affects air exchange and influences sensor response time and harsh condition resilience.
Housing Effects on Response Time
Analysis of how housing design and thermal mass influence the sensor's response time.
6 Mounting and Installation
Filter Membrane Options
Overview of filter membranes (e.g., SF2) for sensor protection against contaminants.
Protective Cover Usage
Purpose and use of the protective cover for sensors during manufacturing processes.
Wettable Flanks for Soldering
Benefits of wettable flanks for improved soldering reliability and inspection.
Mounting on Flex-PCB
Using Flex-PCBs for thermal decoupling and easier sensor exchange in mounting.
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