www.sensirion.com

Version 5 – October 2022

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Datasheet SHT21

Humidity and Temperature Sensor IC

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Fully calibrated

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Digital output, I2C interface

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Low power consumption

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Excellent long-term stability

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DFN type package – reflow solderable

Dimensions

Figure 1: Drawing of SHT21 sensor package, dimensions are

given in mm (1 mm = 0.039 inch), tolerances are ±0.1 mm. The

die pad (center pad) is internally connected to VSS. The NC

pads must be left floating. VSS = GND, SDA = DATA.

Numbering of E/O pads starts at lower right corner (indicated by

notch in die pad) and goes clockwise (compare Table 2).

Sensor Chip

SHT21 features a generation 4C CMOSens® chip.

Besides the capacitive relative humidity sensor and the

band gap temperature sensor, the chip contains an

amplifier, A/D converter, OTP memory and a digital

processing unit.

Material Contents

While the sensor itself is made of Silicon the sensors’

housing consists of a plated Cu lead-frame and green

epoxy-based mold compound. The device is fully RoHS

and WEEE compliant, e.g. free of Pb, Cd and Hg.

Additional Information and Evaluation Kits

Additional information such as Application Notes is

available from the web page www.sensirion.com/sht21.

For more information please contact Sensirion via

info@sensirion.com.

For SHT2x two Evaluation Kits are available: EK-H4, a

four-channel device with Viewer Software, that also serves

for data-logging, and a simple EK-H5 directly connecting

one sensor via USB port to a computer.

1.0

1.0

2.4

0.3

0.4

1.1

SCL

SDA

NC

NC

VSS

VDD

Bottom

View

3.0

2.2

1.4 max

0.3 typ

Product Summary

The SHT21 humidity and temperature sensor of Sensirion

has become an industry standard in terms of form factor

and intelligence: Embedded in a reflow solderable Dual

Flat No leads (DFN) package of 3 x 3mm foot print and

1.1 mm height it provides calibrated, linearized sensor

signals in digital, I2C format.

The SHT2x sensors contain a capacitive type humidity

sensor, a band gap temperature sensor and specialized

analog and digital integrated circuit – all on a single

CMOSens® chip. This yields in an unmatched sensor

performance in terms of accuracy and stability as well as

minimal power consumption.

Every sensor is individually calibrated and tested. Lot

identification is printed on the sensor and an electronic

identification code is stored on the chip – which can be

read out by command. Furthermore, the resolution of

SHT2x can be changed by command (8/12 bit up to

12/14 bit for RH/T) and a checksum helps to improve

communication reliability.

With this set of features and the proven reliability and

long-term stability, the SHT2x sensors offer an

outstanding performance-to-price ratio. For testing SHT2x

two evaluation kits EK-H4 and EK-H5 are available.