SHT21S SENSIRION, SHT21S Datasheet - Page 7

• Manufacturer Part Number: SHT21S
• Description: SENSOR, HUMIDITY & TEMP
• Manufacturer: SENSIRION

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 SHT21S
6 Conversion of Signal Output
After the low pass filter the sensor provides an output
Voltage V
into a physical value.
Resolution is set to 10 bit for relative humidity and 12 bit
for temperature and cannot be changed. The sensor
reading is linearized and hence it can be converted to a
physical value by an easy linear equation.
6.1
With the relative humidity signal output the relative
humidity RH is obtained by the following formula (result in
%RH):
The physical value RH given above corresponds to the
relative humidity above liquid water according to World
Meteorological Organization (WMO). For relative humidity
values above ice RH
as from relative humidity above water RH
temperature t follows – compare also Application Note
“Introduction to Humidity”:
Units are %RH for relative humidity and °C for
temperature. The corresponding coefficients are defined
as follows: β
272.62°C.
6.2
The temperature T is calculated by inserting temperature
signal output S
7 Environmental Stability
The SHT2x sensor series were tested according to AEC-
Q100 Rev. G qualification test method. Sensor
specifications are tested to prevail under the AEC-Q100
temperature grade 2 test conditions listed in Table 9
Sensor performance under other test conditions cannot be
guaranteed and is not part of the sensor specifications.
Especially, no guarantee can be given for sensor
performance in the field or for customer’s specific
application.
13
www.sensirion.com
T
RH
RH
Sensor operation temperature range is -40 to 105°C according to AEC-Q100
temperature grade 2.

i
=


46.85
-6
Relative Humidity Conversion
Temperature Conversion
RH
+
SO
125
w
which as a portion of VDD then is converted

w

exp
T
= 17.62, λ
175.72

into the following formula (result in °C):
VDD
V

 

SO
λ
β
w
i
w
the values need to be transformed



VDD
t
V
t
w
SO

 

= 243.12°C, β
exp

 

λ
β
i
i


t
t

 

i
w
= 22.46, λ
at a certain
Version 1.1 – May 2010
i
13
=
.
Table 5: Qualification tests: HTOL = High Temperature
Operating Lifetime, TC = Temperature Cycles, UHST =
Unbiased Highly accelerated Stress Test, THB = Temperature
Humidity Biased. For details on ESD see Sect. 4.1.
If sensors are qualified for reliability and behavior in
extreme conditions, please make sure that they
experience same conditions as the reference sensor. It
should be taken into account that response times in
assemblies may be longer, hence enough dwell time for
the measurement shall be granted. For detailed
information please consult Application Note “Qualification
Guide”.
8 Packaging
8.1
SHT2x sensors are provided in DFN packaging (in
analogy with QFN packaging). DFN stands for Dual Flat
No leads.
The sensor chip is mounted to a lead frame made of Cu
and plated with Ni/Pd/Au. Chip and lead frame are over
molded by green epoxy-based mold compound. Please
note that side walls of sensors are diced and hence lead
frame at diced edge is not covered with respective
protective coating. The total weight of the sensor is 25mg.
8.2
For SHT2x a filter cap SF2 will be provided. It is designed
for fast response times and compact size. Please find the
datasheet on Sensirion’s web page.
For testing of SHT2x sensors sockets, such as from
Plastronics,
recommended (see e.g. www.locknest.com).
8.3
All SHT21 are laser marked with an alphanumeric, five-
digit code on the sensor – see Figure 12.
14
Environment Standard
THB
ESD immunity HBM 4kV, MM 200V, CDM
Latch-up
HTOL
TC
UHST
According to accuracy and long term drift specification given on Page 2.
Packaging type
Filter Cap and Sockets
Traceability Information
125°C, 408 hours
-50°C - 125°C, 1000 cycles
130°C / 85%RH / ≈2.3bar, 96h Within
85°C / 85%RH, 1000h
750V/500V (corner/other pins)
force current of ±100mA with
T
amb
part
= 80°C
number
10LQ50S13030
Results
Within
specifications
Within
specifications
specifications
Within
specifications
Qualified
Qualified
14
are
7/9