Datasheet
Datasheet SHT21
www.sensirion.com Version 1.1 – May 2010 10/12
16
RH
2
S
1256 RH
In the example given in Figure 15 and Figure 16 the
relative humidity results to be 42.5%RH.
The physical value RH given above corresponds to the
relative humidity above liquid water according to World
Meteorological Organization (WMO). For relative humidity
above ice RH
i
the values need to be transformed from
relative humidity above water RH
w
at temperature t. The
equation is given in the following, compare also
Application Note “Introduction to Humidity:
tλ
tβ
tλ
tβ
RHRH
i
i
w
w
wi
expexp
Units are %RH for relative humidity and °C for
temperature. The corresponding coefficients are defined
as follows: β
w
= 17.62, λ
w
= 243.12°C, β
i
= 22.46, λ
i
=
272.62°C.
6.2 Temperature Conversion
The temperature T is calculated by inserting temperature
signal output S
T
into the following formula (result in °C), no
matter which resolution is chosen:
16
T
2
S
175.7246.85 T
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
16
.
Environment Standard Results
17
HTOL 125°C, 408 hours Within
specifications
TC -50°C - 125°C, 1000 cycles Within
specifications
UHST 130°C / 85%RH / ≈2.3bar, 96h
Within
specifications
THB 85°C / 85%RH, 1000h Within
specifications
ESD immunity
HBM 4kV, MM 200V, CDM
750V/500V (corner/other pins)
Qualified
Latch-up force current of ±100mA with
T
amb
= 125°C
Qualified
Table 9: Performed qualification test series. 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.
16
Temperature range is -40 to 105°C (AEC-Q100 temperature grade 2).
17
According to accuracy and long term drift specification given on Page 2.
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.
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 “Testing
Guide”.
8 Packaging
8.1 Packaging Type
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 Filter Cap and Sockets
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, part number 10LQ50S13030 are
recommended (see e.g. www.locknest.com).
8.3 Traceability Information
All SHT2x are laser marked with an alphanumeric, five-
digit code on the sensor – see Figure 19.
The marking on the sensor consists of two lines with five
digits each. The first line denotes the sensor type
(SHT21). The first digit of the second line defines the
output mode (D = digital, Sensibus and I
2
C, P = PWM, S =
SDM). The second digit defines the manufacturing year (0
= 2010, 1 = 2011, etc.). The last three digits represent an
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.