Overview
The SHT21 humidity and temperature sensor, produced by Sensirion AG, has become an industry standard due to its compact form factor and advanced intelligence. Embedded in a reflow solderable Dual Flat No leads (DFN) package with a footprint of 3 x 3mm and a height of 1.1mm, this sensor provides calibrated, linearized sensor signals in digital format via the I2C interface. The SHT21 integrates a capacitive relative humidity sensor and a band gap temperature sensor, along with an amplifier, A/D converter, OTP memory, and a digital processing unit on a single CMOSens® chip. This integration ensures unmatched sensor performance in terms of accuracy, stability, and minimal power consumption.
Key Specifications
| Parameter | Value | Units |
|---|---|---|
| Humidity Range | 0 - 100 | % RH |
| Humidity Resolution | 0.04 (12 bit), 0.7 (8 bit) | % RH |
| Humidity Accuracy | ±2 | % RH |
| Humidity Response Time | 8 seconds (tau 63%) | |
| Temperature Range | -40 to +125 | °C |
| Temperature Resolution | 0.01 | °C |
| Temperature Accuracy | ±0.3 | °C |
| Supply Voltage | 2.1 - 3.6 V | |
| Power Consumption | 80 μW (at 12 bit, 3V, 1 measurement/s) | |
| Interface | I2C | |
| Package Type | DFN-6 | |
| Dimensions | 3 x 3 mm footprint, 1.1 mm height |
Key Features
- Fully calibrated and tested, with individual calibration and lot identification.
- Low power consumption, making it suitable for a wide range of applications.
- Excellent long-term stability and accuracy.
- Embedded in a reflow solderable DFN package.
- Digital output via I2C interface, with adjustable resolution (8/12 bit up to 12/14 bit for RH/T).
- RoHS and WEEE compliant, free of Pb, Cd, and Hg).
Applications
- Remote weather stations and environmental monitoring systems.
- Gardens and greenhouses for soil moisture and temperature measurement.
- Industrial automation and control systems requiring precise humidity and temperature measurements).
- Medical devices and healthcare equipment where accurate environmental monitoring is crucial).
- Consumer electronics, such as smart home devices and air quality monitors).
Q & A
- What is the operating range of the SHT21 sensor?
The SHT21 operates within a humidity range of 0-100% RH and a temperature range of -40 to +125°C).
- What is the power consumption of the SHT21 sensor?
The power consumption is approximately 80 μW at 12 bit resolution, 3V supply, and 1 measurement per second).
- How does the SHT21 communicate with other devices?
The SHT21 communicates via the I2C protocol over a two-wire serial interface).
- Is the SHT21 RoHS compliant?
Yes, the SHT21 is RoHS and WEEE compliant, free of Pb, Cd, and Hg).
- What is the response time of the SHT21 sensor?
The humidity response time is 8 seconds (tau 63%), and the temperature response time is 30 seconds).
- How is the SHT21 sensor calibrated?
Each SHT21 sensor is individually calibrated and tested, with lot identification printed on the sensor and an electronic identification code stored on the chip).
- Can the SHT21 be used in extreme conditions?
The sensor is stable within the recommended normal range, but prolonged exposure to extreme conditions may accelerate ageing and temporarily offset the RH signal).
- How does the SHT21 enter sleep mode?
The SHT21 enters sleep mode automatically after each measurement and sending the stop command; it remains dormant until started again).
- What are the dimensions of the SHT21 package?
The SHT21 package has a footprint of 3 x 3 mm and a height of 1.1 mm).
- Is the SHT21 compatible with Arduino boards?
Yes, the SHT21 is compatible with Arduino boards and can communicate directly via the I2C protocol).
