SHT21S SENSIRION, SHT21S Datasheet

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SHT21S

Manufacturer Part Number
SHT21S
Description
SENSOR, HUMIDITY & TEMP
Manufacturer
SENSIRION
Datasheets

Specifications of SHT21S

Humidity Range
0 - 100% RH
Sensor Output
SDM - Convertible To Analogue
Sensor Terminals
SMD
Response Time
8s
Supply Voltage Range
2.1V To 3.6V
Accuracy
2% RH
Supply Voltage
3VDC
Rohs Compliant
Yes
Capacitance
0µF
Sensing Accuracy
2%
Operating Temperature Range
-40°C To +125°C
Msl
MSL 2 - 1 Year
Datasheet SHT21
Humidity and Temperature Sensor
 Fully calibrated
 Digital output, I
 Low power consumption
 Excellent long term stability
 DFN type package – reflow solderable
Dimensions
Figure 1: Drawing of SHT21 sensor package, dimensions are
given in mm (1mm = 0.039inch), tolerances are ±0.1mm. NC
and die pad (center pad) are internally connected to VSS. They
may 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).
www.sensirion.com
Product Summary
SHT21, the new humidity and temperature sensor of
Sensirion is about to set new standards in terms of size
and intelligence: Embedded in a reflow solderable Dual
Flat No leads (DFN) package of 3 x 3mm foot print and
1.1mm height it provides calibrated, linearized signals in
digital, true I
With a completely new designed CMOSens® chip, a
reworked capacitive type humidity sensor and an
improved band gap temperature sensor the performance
has been lifted even beyond the outstanding level of the
previous sensor generation (SHT1x and SHT7x). For
example, measures have been taken to stabilize the
behavior at high humidity levels.
2
1.0
C format.
0.4
3.0
2.4
2.2
0.8 typ
1.0
0.3 typ
0.3
2
C interface
Bottom View
NC
NC
1.1
VDD
VSS
Version 1.1 – May 2010
SCL
SDA
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 SHT21 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.
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
SHT21 can be changed by command (8/12bit up to
12/14bit for RH/T), low battery can be detected and a
checksum helps to improve communication reliability.
With made improvements and the miniaturization of the
sensor the performance-to-price ratio has been improved
– and eventually, any device should benefit from the
cutting edge energy saving operation mode. For testing
SHT21 a new evaluation Kit EK-H4 is available.
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SHT21S Summary of contents

Page 1

... DFN type package – reflow solderable Product Summary SHT21, the new humidity and temperature sensor of Sensirion is about to set new standards in terms of size and intelligence: Embedded in a reflow solderable Dual Flat No leads (DFN) package 3mm foot print and 1.1mm height it provides calibrated, linearized signals in ...

Page 2

... Time for achieving 63 step function, valid at 25°C and 1m/s airflow. 4 Normal operating range: 0-80%RH, beyond this limit sensor may read a reversible offset with slow kinetics (<3%RH after 200hours at 90%RH). For more details please see Section 1.1 of the Users Guide. www.sensirion.com Temperature typ max Units Parameter 0 ...

Page 3

... Datasheet SHT21 Users Guide SHT2x 1 Extended Specification For details on how Sensirion is specifying and testing accuracy performance please consult Application Note “Statement on Sensor Specification”. 1.1 Operating Range The sensor works stable within recommended Normal Range – see Figure 4. Long term exposure to conditions outside Normal Range, especially at humidity > ...

Page 4

... DFN pads are soldered to. 9 The solder mask is understood to be the insulating layer on top of the PCB covering the connecting lines. www.sensirion.com centered on the thermal land area. It can also be split in two openings. Due to the low mounted height of the DFN, “no clean” ...

Page 5

... Manufacturing area shall be well ventilated. For more detailed information please consult the document “Handling Instructions” or contact Sensirion. 2.3 Reconditioning Procedure As stated above extreme conditions or exposure to solvent vapors may offset the sensor. The following reconditioning ...

Page 6

... For the choice of resistor size please take bus capacity requirements into account (compare Table 5). It should be noted that pull-up resistors may be included in I/O circuits www.sensirion.com of MCUs. See Table 4 and Table 5 for detailed I/O characteristic of the sensor. 4 Electrical Characteristics ...

Page 7

... Sections please refer to the following website: http://www.standardics.nxp.com/support/i2c/. Please note that all sensors are set to the same I address, as defined in Section 5.3. 14 Furthermore, please note, that Sensirion provides an exemplary sample code on its home page – compare www.sensirion.com/sht21. 5.1 Start Up Sensor As a first step, the sensor is powered up to the chosen supply voltage VDD (between 2 ...

Page 8

... For both modes, since the maximum resolution of a measurement is 14 bit, the two last least significant bits (LSBs, bits 43 and 44) are used for transmitting status information. Bit 1 of the two LSBs indicates the measurement type (‘0’: temperature, ‘1’ humidity). Bit 0 is currently not assigned. www.sensirion.com other Figure 16 No Hold master communication sequence – ...

Page 9

... Application Note “Electronic Identification Code” – downloaded from the web page www.sensirion.com/SHT21. ‘0’ ‘1’ 6 Conversion of Signal Output Default resolution is set to 12 bit relative humidity and 14 bit temperature reading. Measured data are transferred in two byte packages, i ...

Page 10

... The last three digits represent an Qualified alphanumeric tracking code. That code can be decoded by Sensirion only and allows for tracking on batch level through production, calibration and testing – and will be provided upon justified request. Version 1.1 – May 2010 ...

Page 11

... Figure 21: Second label on reel: For Device Type and Part Order Number (See Packaging Information on page 2), Delivery Date (also Date Code) is date of packaging of sensors (DD = day month, YYYY = year), CCCC = Sensirion order number. 8.4 Shipping Package SHT2x are provided in tape & reel shipment packaging, sealed into antistatic ESD bags ...

Page 12

... WARRANTIES, INCLUDING WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE EXPRESSLY EXCLUDED AND DECLINED. SENSIRION is only liable for defects of this product arising under the conditions of operation provided for in the data sheet and proper use of the goods. SENSIRION explicitly disclaims all warranties, express or implied, for any period during which the goods are operated or stored not in accordance with the technical specifications ...

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