SHT1x Datasheet by DFRobot

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www.sensirion.com Version 4.3 – May 2010 1/11
Datasheet SHT1x (SHT10, SHT11, SHT15)
Humidity and Temperature Sensor
Fully calibrated
Digital output
Low power consumption
Excellent long term stability
SMD type package – reflow solderable
Dimensions
Figure 1: Drawing of SHT1x sensor packaging, dimensions in
mm (1mm = 0.039inch). Sensor label gives “11” for SHT11 as
an example. Contacts are assigned as follows: 1:GND, 2:DATA,
3:SCK, 4:VDD.
Sensor Chip
SHT1x V4 for which this datasheet applies features a
version 4 Silicon sensor chip. Besides the humidity and
temperature sensors the chip contains an amplifier, A/D
converter, OTP memory and a digital interface. V4 sensors
can be identified by the alpha-numeric traceability code on
the sensor cap – see example “A5Zcode on Figure 1.
Material Contents
While the sensor is made of a CMOS chip the sensor
housing consists of an LCP cap with epoxy glob top on an
FR4 substrate. The device is fully RoHS and WEEE
compliant, thus it is free of Pb, Cd, Hg, Cr(6+), PBB and
PBDE.
Evaluation Kits
For sensor trial measurements, for qualification of the
sensor or even experimental application (data logging) of
the sensor there is an evaluation kit EK-H4 available
including SHT71 (same sensor chip as SHT1x) and 4
sensor channels, hard and software to interface with a
computer. For other evaluation kits please check
www.sensirion.com/humidity.
Product Summary
SHT1x (including SHT10, SHT11 and SHT15) is
Sensirion’s family of surface mountable relative humidity
and temperature sensors. The sensors integrate sensor
elements plus signal processing on a tiny foot print and
provide a fully calibrated digital output. A unique
capacitive sensor element is used for measuring relative
humidity while temperature is measured by a band-gap
sensor. The applied CMOSens® technology guarantees
excellent reliability and long term stability. Both sensors
are seamlessly coupled to a 14bit analog to digital
converter and a serial interface circuit. This results in
superior signal quality, a fast response time and
insensitivity to external disturbances (EMC).
Each SHT1x is individually calibrated in a precision
humidity chamber. The calibration coefficients are
programmed into an OTP memory on the chip. These
coefficients are used to internally calibrate the signals
from the sensors. The 2-wire
serial interface and internal
voltage regulation allows for easy and fast system
integration. The tiny size and low power consumption
makes SHT1x the ultimate choice for even the most
demanding applications.
SHT1x is supplied in a surface-mountable LCC (L
eadless
Chip Carrier) which is approved for standard reflow
soldering processes. The same sensor is also available
with pins (SHT7x) or on flex print (SHTA1).
A5Z
1
2
NC
NC
NC
NC
NC
NC
3.3
±0.1
4.93
±0.05
2.0
±0.1
1.5
±0.1
7.47
±0.05
4.2
±0.1
1.2
7
±0.05
1.83
±0.05
5.2
±0.2
0.6
±0.1
s
ensor opening
2.5 ±0.1
0.8
±0.1
3
4
11
0.95
±0.1
1.5 ±0.2
2.6
MAX
2.2 MAX
SENSIRION THE sense»: COMPANY X
Datasheet SHT1x
www.sensirion.com Version 4.3 May 2010 2/11
Sensor Performance
Relative Humidity123
Parameter Condition min typ max Units
0.4 0.05 0.05 %RH
Resolution 1 8 12 12 bit
typical 4.5 %RH
Accuracy 2
SHT10 maximal see Figure 2
typical 3.0 %RH
Accuracy 2
SHT11 maximal see Figure 2
typical 2.0 %RH
Accuracy 2
SHT15 maximal see Figure 2
Repeatability 0.1 %RH
Hysteresis 1 %RH
Non-linearity linearized <<1 %RH
Response time 3 (63%) 8 s
Operating Range
0 100 %RH
Long term drift 4 normal < 0.5 %RH/yr
SHT11
SHT15
SHT10
± 0
± 2
± 4
± 6
± 8
± 10
0 10 20 30 40 50 60 70 80 90 100
Relative Humidity (%RH)
RH (%RH)
Figure 2: Maximal RH-tolerance at 25°C per sensor type.
Electrical and General Items
Parameter Condition min typ max Units
Source Voltage 2.4 3.3 5.5 V
sleep 2 5 µW
measuring 3 mW
Power
Consumption 5 average 90 µW
Communication digital 2-wire interface, see Communication
Storage 10 – 50°C (0 – 125°C peak), 20 – 60%RH
1 The default measurement resolution of is 14bit for temperature and 12bit for
humidity. It can be reduced to 12/8bit by command to status register.
2 Accuracies are tested at Outgoing Quality Control at 25°C (77°F) and 3.3V.
Values exclude hysteresis and are applicable to non-condensing environments
only.
3 Time for reaching 63% of a step function, valid at 25°C and 1 m/s airflow.
Temperature45
Parameter Condition min typ max Units
0.04 0.01 0.01 °C
Resolution 1 12 14 14 bit
typical 0.5 °C
Accuracy 2
SHT10 maximal see Figure 3
typical 0.4 °C
Accuracy 2
SHT11 maximal see Figure 3
typical 0.3 °C
Accuracy 2
SHT15 maximal see Figure 3
Repeatability 0.1 °C
-40 123.8
°C
Operating Range
-40 254.9
°F
Response Time 6
(63%) 5 30 s
Long term drift < 0.04
°C/yr
SHT11
SHT15
SHT10
± 0.0
± 0.5
± 1.0
± 1.5
± 2.0
± 2.5
± 3.0
-40 -20 0 20 40 60 80 100
Temperature (°C)
T (°C)
Figure 3: Maximal T-tolerance per sensor type.
Packaging Information
Sensor Type Packaging Quantity Order Number
SHT10 Tape & Reel 2000 1-100218-04
Tape & Reel 100 1-100051-04
Tape & Reel 400 1-100098-04
SHT11 Tape & Reel 2000 1-100524-04
Tape & Reel 100 1-100085-04
SHT15 Tape & Reel 400 1-100093-04
This datasheet is subject to change and may be
amended without prior notice.
4 Value may be higher in environments with high contents of volatile organic
compounds. See Section 1.3 of Users Guide.
5 Values for VDD=3.3V at 25°C, average value at one 12bit measurement
per second.
6 Response time depends on heat capacity of and thermal resistance to
sensor substrate.
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www.sensirion.com Version 4.3 – May 2010 3/11
Users Guide SHT1x
1 Application Information
1.1 Operating Conditions
Sensor works stable within recommended normal range
see Figure 4. Long term exposures to conditions outside
normal range, especially at humidity >80%RH, may
temporarily offset the RH signal (+3 %RH after 60h). After
return to normal range it will slowly return towards
calibration state by itself. See Section 1.4 “Reconditioning
Procedure” to accelerate eliminating the offset. Prolonged
exposure to extreme conditions may accelerate ageing.
Max. Range
Normal
Range
0
20
40
60
80
100
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Relative Humidity (%)
Figure 4: Operating Conditions
1.2 Soldering instructions
For soldering SHT1x standard reflow soldering ovens may
be used. The sensor is qualified to withstand soldering
profile according to IPC/JEDEC J-STD-020D with peak
temperatures at 260°C during up to 40sec including Pb-
free assembly in IR/Convection reflow ovens.
Figure 5: Soldering profile according to JEDEC standard. TP <=
260°C and tP < 40sec for Pb-free assembly. TL < 220°C and tL <
150sec. Ramp-up/down speeds shall be < 5°C/sec.
For soldering in Vapor Phase Reflow (VPR) ovens the
peak conditions are limited to TP < 233°C during tP <
60sec and ramp-up/down speeds shall be limited to
10°C/sec. For manual soldering contact time must be
limited to 5 seconds at up to 350°C7.
7 233°C = 451°F, 260°C = 500°F, 350°C = 662°F
IMPORTANT: After soldering the devices should be stored
at >75%RH for at least 12h to allow the polymer to re-
hydrate. Otherwise the sensor may read an offset that
slowly disappears if exposed to ambient conditions.
Alternatively the re-hydration process may be performed at
ambient conditions (>40%RH) during more than 5 days.
In no case, neither after manual nor reflow soldering, a
board wash shall be applied. Therefore it is strongly
recommended to use no-clean” solder paste. In case of
application with exposure of the sensor to corrosive gases
or condensed water (i.e. environments with high relative
humidity) the soldering pads shall be sealed (e.g.
conformal coating) to prevent loose contacts or short cuts.
For the design of the SHT1x footprint it is recommended to
use dimensions according to Figure 7. Sensor pads are
coated with 35µm Cu, 5µm Ni and 0.1µm Au.
Figure 6: Rear side electrodes of sensor, view from top side.
Figure 7: Recommended footprint for SHT1x. Values in mm.
1.3 Storage Conditions and Handling Instructions
It is of great importance to understand that a humidity
sensor is not a normal electronic component and needs to
be handled with care. Chemical vapors at high
concentration in combination with long exposure times
may offset the sensor reading.
For these reasons it is recommended to store the sensors
in original packaging including the sealed ESD bag at
1
.27
1.97
0.80
1.38
2.47
1.07
Ø0.60
1.27
1.27
7.47
0.8
3.48
0.47
4.61
1.27
1.8
1.8
7.08
No copper in this field
1.27
1.27
7.50
Temperature
Time
tP
T
P
T
L
T
S
(max)
tL
preheating
critical zone
SENSIRION nus SENSOR (OMFANV
Datasheet SHT1x
www.sensirion.com Version 4.3 May 2010 4/11
following conditions: Temperature shall be in the range of
10°C 50°C (0 125°C for limited time) and humidity at
20 60%RH (sensors that are not stored in ESD bags).
For sensors that have been removed from the original
packaging we recommend to store them in ESD bags
made of metal-in PE-HD8.
In manufacturing and transport the sensors shall be
prevented of high concentration of chemical solvents and
long exposure times. Out-gassing of glues, adhesive tapes
and stickers or out-gassing packaging material such as
bubble foils, foams, etc. shall be avoided. Manufacturing
area shall be well ventilated.
For more detailed information please consult the
document Handling Instructions” or contact Sensirion.
1.4 Reconditioning Procedure
As stated above extreme conditions or exposure to solvent
vapors may offset the sensor. The following reconditioning
procedure may bring the sensor back to calibration state:
Baking: 100 – 105°C at < 5%RH for 10h
Re-Hydration: 20 – 30°C at ~ 75%RH for 12h 9.
1.5 Temperature Effects
Relative humidity reading strongly depends on
temperature. Therefore, it is essential to keep humidity
sensors at the same temperature as the air of which the
relative humidity is to be measured. In case of testing or
qualification the reference sensor and test sensor must
show equal temperature to allow for comparing humidity
readings.
If the SHT1x shares a PCB with electronic components
that produce heat it should be mounted in a way that
prevents heat transfer or keeps it as low as possible.
Measures to reduce heat transfer can be ventilation,
reduction of copper layers between the SHT1x and the
rest of the PCB or milling a slit into the PCB around the
sensor (see Figure 8).
Figure 8: Top view of example of mounted SHT1x with slits
milled into PCB to minimize heat transfer.
8 For example, 3M antistatic bag, product 1910 with zipper .
9 75%RH can conveniently be generated with saturated NaCl solution.
100 – 105°C correspond to 212 – 221°F, 20 – 30°C correspond to 68 – 86°F
Furthermore, there are self-heating effects in case the
measurement frequency is too high. Please refer to
Section 3.3 for detailed information.
1.6 Light
The SHT1x is not light sensitive. Prolonged direct
exposure to sunshine or strong UV radiation may age the
housing.
1.7 Membranes
SHT1x does not contain a membrane at the sensor
opening. However, a membrane may be added to prevent
dirt and droplets from entering the housing and to protect
the sensor. It will also reduce peak concentrations of
chemical vapors. For optimal response times the air
volume behind the membrane must be kept minimal.
Sensirion recommends and supplies the SF1 filter cap for
optimal IP54 protection (for higher protection i.e. IP67 -
SF1 must be sealed to the PCB with epoxy). Please
compare Figure 9.
Figure 9: Side view of SF1 filter cap mounted between PCB and
housing wall. Volume below membrane is kept minimal.
1.8 Materials Used for Sealing / Mounting
Many materials absorb humidity and will act as a buffer
increasing response times and hysteresis. Materials in the
vicinity of the sensor must therefore be carefully chosen.
Recommended materials are: Any metals, LCP, POM
(Delrin), PTFE (Teflon), PE, PEEK, PP, PB, PPS, PSU,
PVDF, PVF.
For sealing and gluing (use sparingly): Use high filled
epoxy for electronic packaging (e.g. glob top, underfill),
and Silicone. Out-gassing of these materials may also
contaminate the SHT1x (see Section 1.3). Therefore try to
add the sensor as a last manufacturing step to the
assembly, store the assembly well ventilated after
manufacturing or bake at >50°C for 24h to outgas
contaminants before packing.
1.9 Wiring Considerations and Signal Integrity
Carrying the SCK and DATA signal parallel and in close
proximity (e.g. in wires) for more than 10cm may result in
cross talk and loss of communication. This may be
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SHT1x
membrane
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Datasheet SHT1x
www.sensirion.com Version 4.3 May 2010 5/11
resolved by routing VDD and/or GND between the two
data signals and/or using shielded cables. Furthermore,
slowing down SCK frequency will possibly improve signal
integrity. Power supply pins (VDD, GND) must be
decoupled with a 100nF capacitor if wires are used.
Capacitor should be placed as close to the sensor as
possible. Please see the Application Note “ESD, Latch-up
and EMC” for more information.
1.10 ESD (Electrostatic Discharge)
ESD immunity is qualified according to MIL STD 883E,
method 3015 (Human Body Model at 2 kV).
Latch-up immunity is provided at a force current of
100mA with Tamb = 80°C according to JEDEC78A. See
Application Note ESD, Latch-up and EMC” for more
information.
2 Interface Specifications
Pin
Name Comment
1 GND Ground
2 DATA Serial Data, bidirectional
3 SCK Serial Clock, input only
4 VDD Source Voltage
NC
NC Must be left unconnected
Table 1: SHT1x pin assignment, NC remain floating.
2.1 Power Pins (VDD, GND)
The supply voltage of SHT1x must be in the range of 2.4 –
5.5V, recommended supply voltage is 3.3V. Power supply
pins Supply Voltage (VDD) and Ground (GND) must be
decoupled with a 100 nF capacitorsee Figure 10.
The serial interface of the SHT1x is optimized for sensor
readout and effective power consumption. The sensor
cannot be addressed by I2C protocol; however, the sensor
can be connected to an I2C bus without interference with
other devices connected to the bus. The controller must
switch between the protocols.
Figure 10: Typical application circuit, including pull up resistor
RP and decoupling of VDD and GND by a capacitor.
2.2 Serial clock input (SCK)
SCK is used to synchronize the communication between
microcontroller and SHT1x. Since the interface consists of
fully static logic there is no minimum SCK frequency.
2.3 Serial data (DATA)
The DATA tri-state pin is used to transfer data in and out
of the sensor. For sending a command to the sensor,
DATA is valid on the rising edge of the serial clock (SCK)
and must remain stable while SCK is high. After the falling
edge of SCK the DATA value may be changed. For safe
communication DATA valid shall be extended TSU and THO
before the rising and after the falling edge of SCK,
respectively see Figure 11. For reading data from the
sensor, DATA is valid TV after SCK has gone low and
remains valid until the next falling edge of SCK.
To avoid signal contention the microcontroller must only
drive DATA low. An external pull-up resistor (e.g. 10kΩ) is
required to pull the signal high it should be noted that
pull-up resistors may be included in I/O circuits of
microcontrollers. See Table 2 for detailed I/O characteristic
of the sensor.
2.4 Electrical Characteristics
The electrical characteristics such as power consumption,
low and high level input and output voltages depend on
the supply voltage. Table 2 gives electrical characteristics
of SHT1x with the assumption of 5V supply voltage if not
stated otherwise.
Parameter Conditions min typ max Units
Power supply DC10 2.4 3.3 5.5 V
measuring 0.55 1 mA
average11 2 28 µA
Supply current sleep 0.3 1.5 µA
Low level output
voltage IOL < 4 mA 0 250 mV
High level output
voltage RP < 25 kΩ 90% 100%
VDD
Low level input
voltage Negative going
0% 20% VDD
High level input
voltage Positive going 80% 100%
VDD
Input current on pads
1 µA
on 4 mA
Output current Tri-stated (off) 10 20 µA
Table 2: SHT1x DC characteristics. RP stands for pull up
resistor, while IOL is low level output current.
10 Recommended voltage supply for highest accuracy is 3.3V, due to sensor
calibration.
11 Minimum value with one measurement of 8bit resolution without OTP reload
per second. Typical value with one measurement of 12bit resolution per
second.
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11
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NC
NC
NC
NC
NC
1
2
3
4
Micro-
Controller
(Master)
GND
2.4
5.5V
DATA
SCK
VDD
R
P
VDD
GND
SHT1x
(Slave)
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11
100nF
10
k
Ω
SENSIRION rue sensor; (OMF'ANY
Datasheet SHT1x
www.sensirion.com Version 4.3 May 2010 6/11
Absolute maximum ratings for VDD versus GND are +7V
and -0.3V. Exposure to absolute maximum rating
conditions for extended periods may affect the sensor
reliability (e.g. hot carrier degradation, oxide breakdown).
For proper communication with the sensor it is essential to
make sure that signal design is strictly within the limits
given in Table 3 and Figure 11.
Figure 11: Timing Diagram, abbreviations are explained in
Table 3. Bold DATA line is controlled by the sensor, plain DATA
line is controlled by the micro-controller. Note that DATA valid
read time is triggered by falling edge of anterior toggle.
Parameter Conditions min typ max
Units
VDD > 4.5V
0 0.1 5 MHz
FSCK SCK Frequency VDD < 4.5V
0 0.1 1 MHz
TSCKx
SCK hi/low time 100
ns
TR/TF
SCK rise/fall time 1 200
* ns
OL = 5pF 3.5 10 20 ns
TFO DATA fall time OL = 100pF
30 40 200
ns
TRO DATA rise time ** ** ** ns
TV DATA valid time 200
250
*** ns
TSU DATA setup time 100
150
*** ns
THO DATA hold time 10 15 **** ns
* TR_max + TF_max = (FSCK)-1 – TSCKH – TSCKL
** TR0 is determined by the RP*Cbus time-constant at DATA line
*** TV_max and TSU_max depend on external pull-up resistor (RP) and total bus
line capacitance (Cbus) at DATA line
**** TH0_max < TV – max (TR0, TF0)
Table 3: SHT1x I/O signal characteristics, OL stands for Output
Load, entities are displayed in Figure 11.
3 Communication with Sensor
3.1 Start up Sensor
As a first step the sensor is powered up to chosen supply
voltage VDD. The slew rate during power up shall not fall
below 1V/ms. After power-up the sensor needs 11ms to
get to Sleep State. No commands must be sent before
that time.
3.2 Sending a Command
To initiate a transmission, a Transmission Start sequence
has to be issued. It consists of a lowering of the DATA line
while SCK is high, followed by a low pulse on SCK and
raising DATA again while SCK is still high – see Figure 12.
Figure 12: "Transmission Start" sequence
The subsequent command consists of three address bits
(only ‘000’ is supported) and five command bits. The
SHT1x indicates the proper reception of a command by
pulling the DATA pin low (ACK bit) after the falling edge of
the 8th SCK clock. The DATA line is released (and goes
high) after the falling edge of the 9th SCK clock.
Command Code
Reserved 0000x
Measure Temperature 00011
Measure Relative Humidity 00101
Read Status Register 00111
Write Status Register 00110
Reserved 0101x-1110x
Soft reset, resets the interface, clears the
status register to default values. Wait minimum
11 ms before next command
11110
Table 4: SHT1x list of commands
3.3 Measurement of RH and T
After issuing a measurement command (‘00000101’ for
relative humidity, ‘00000011’ for temperature) the
controller has to wait for the measurement to complete.
This takes a maximum of 20/80/320 ms for a 8/12/14bit
measurement. The time varies with the speed of the
internal oscillator and can be lower by up to 30%. To
signal the completion of a measurement, the SHT1x pulls
data line low and enters Idle Mode. The controller must
wait for this Data Ready signal before restarting SCK to
readout the data. Measurement data is stored until
readout, therefore the controller can continue with other
tasks and readout at its convenience.
Two bytes of measurement data and one byte of CRC
checksum (optional) will then be transmitted. The micro
controller must acknowledge each byte by pulling the
DATA line low. All values are MSB first, right justified (e.g.
the 5th SCK is MSB for a 12bit value, for a 8bit result the
first byte is not used).
DATA valid
read
DATA valid write
DATA
SCK
8
0%
2
0%
8
0%
2
0%
T
V
T
SCKL
T
SU
T
HO
T
SCK
T
SCKH
T
R
T
F
T
RO
T
FO
DATA
SCK
8
0%
2
0%
8
0%
2
0%
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Datasheet SHT1x
www.sensirion.com Version 4.3 May 2010 7/11
Communication terminates after the acknowledge bit of
the CRC data. If CRC-8 checksum is not used the
controller may terminate the communication after the
measurement data LSB by keeping ACK high. The device
automatically returns to Sleep Mode after measurement
and communication are completed.
Important: To keep self heating below 0.1°C, SHT1x
should not be active for more than 10% of the time e.g.
maximum one measurement per second at 12bit accuracy
shall be made.
3.4 Connection reset sequence
If communication with the device is lost the following signal
sequence will reset the serial interface: While leaving
DATA high, toggle SCK nine or more times see Figure
13. This must be followed by a Transmission Start
sequence preceding the next command. This sequence
resets the interface only. The status register preserves its
content.
Figure 13: Connection Reset Sequence
3.5 CRC Checksum calculation
The whole digital transmission is secured by an 8bit
checksum. It ensures that any wrong data can be detected
and eliminated. As described above this is an additional
feature of which may be used or abandoned. Please
consult Application Note “CRC Checksum for information
on how to calculate the CRC.
3.6 Status Register
Some of the advanced functions of the SHT1x such as
selecting measurement resolution, end-of-battery notice,
use of OTP reload or using the heater may be activated by
sending a command to the status register. The following
section gives a brief overview of these features.
After the command Status Register Read or Status
Register Write see Table 4 the content of 8 bits of the
status register may be read out or written. For the
communication compare Figure 14 and Figure 15 the
assignation of the bits is displayed in Table 5.
0
0
0
0
0
1
1
0
Status Register
TS
ACK
Bit 7
ACK
Figure 14: Status Register Write
Figure 15: Status Register Read
Examples of full communication cycle are displayed in
Figure 16 and Figure 17.
0
0
0
Command 0
0
MSB
TS
Wait for
DATA ready
ACK
LSB Checksum
LSb
ACK
ACK
Figure 16: Overview of Measurement Sequence. TS = Trans-
mission Start, MSB = Most Significant Byte, LSB = Last
Significant Byte, LSb = Last Significant Bit.
Figure 17: Example RH measurement sequence for value “0000’0100“0011’0001” = 1073 = 35.50%RH (without temperature
compensation). DATA valid times are given and referenced in boxes on DATA line. Bold DATA lines are controlled by sensor while plain
lines are controlled by the micro-controller.
0
0
0
0
0
1
1
1
Status Register Checksum
TS
ACK
Bit 7
ACK
Bit 7
ACK
DATA
SCK
8
0%
2
0%
8
0%
2
0%
1
2
3
2
4 - 8
9
Transmission Start
DATA
DATA
SCK
SCK
SCK
DATA
A2
A1
A0
C4
C3 C2 C1
C0 ACK
15 14
13
12 11 10
9
8 ACK 7
6 5
4 3
2 1
0 ACK
7 6
5 4
3
2 1 0
ACK
Transmission Start
Address = ‘000
Command = ‘00101
12bit Humidity Data
CRC
-
8 Checksum
Transmission Start
Measurement
(80ms for 12bit)
Sleep
(wait for next
measurement)
Idle Bits
Skip ACK to end trans
mission
(if
no CR
C is used)
Sensor pulls DATA line low after
completion of measurement
MSb
LSb
MSb
LSb
15
14
13
12
11
10
9
8
ACK
7
6
5
4
3
2
1
0
A2
A1
A0
C4
C3
C2
C1
C0
ACK
7
6
5
4
3
2
1
0
ACK
ACK
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Datasheet SHT1x
www.sensirion.com Version 4.3 May 2010 8/11
Bit Type Description Default
7 reserved 0
6 R
End of Battery (low voltage
detection)
‘0’ for VDD > 2.47
‘1’ for VDD < 2.47
X
No default value,
bit is only updated
after a
measurement
5 reserved 0
4 reserved 0
3 For Testing only, do not use
0
2 R/W Heater 0 off
1 R/W no reload from OTP 0 reload
0 R/W
’1’ = 8bit RH / 12bit Temp.
resolution
’0’ = 12bit RH / 14bit Temp.
resolution
0 12bit RH
14bit Temp.
Table 5: Status Register Bits
Measurement resolution: The default measurement
resolution of 14bit (temperature) and 12bit (humidity) can
be reduced to 12 and 8bit. This is especially useful in high
speed or extreme low power applications.
End of Battery function detects and notifies VDD voltages
below 2.47V. Accuracy is 0.05V.
Heater: An on chip heating element can be addressed by
writing a command into status register. The heater may
increase the temperature of the sensor by 5 – 10°C12
beyond ambient temperature. The heater draws roughly
8mA @ 5V supply voltage.
For example the heater can be helpful for functionality
analysis: Humidity and temperature readings before and
after applying the heater are compared. Temperature shall
increase while relative humidity decreases at the same
time. Dew point shall remain the same.
Please note: The temperature reading will display the
temperature of the heated sensor element and not
ambient temperature. Furthermore, the sensor is not
qualified for continuous application of the heater.
OTP reload: With this operation the calibration data is
uploaded to the register before each measurement. This
may be deactivated for reducing measurement time by
about 10ms.
4 Conversion of Signal Output
4.1 Relative Humidity
For compensating non-linearity of the humidity sensor
see Figure 18 and for obtaining the full accuracy of the
sensor it is recommended to convert the humidity readout
12 Corresponds to 9 – 18°F
(SORH) with the following formula with coefficients given in
Table 6:
2
RH3RH21linear SOcSOccRH (%RH)
SORH c1 c2 c3
12 bit -2.0468 0.0367 -1.5955E-6
8 bit -2.0468 0.5872 -4.0845E-4
Table 6: V4 humidity conversion coefficients
The values given in Table 6 are optimized coefficients for
V4 sensors. The parameter set for V3 sensors, which has
been proposed in earlier datasheets, still applies and is
provided by Sensirion upon request.
Values higher than 99% RH indicate fully saturated air and
must be processed and displayed as 100%RH13. Please
note that the humidity sensor has no significant voltage
dependency.
0%
20%
40%
60%
80%
100%
0 500 1000 1500 2000 2500 3000 3500
SORH sensor readout (12bit)
Relative Humidity
Figure 18: Conversion from SORH to relative humidity
4.2 Temperature compensation of Humidity Signal
For temperatures significantly different from 25°C (~77°F)
the humidity signal requires temperature compensation.
The temperature correction corresponds roughly to
0.12%RH/°C @ 50%RH. Coefficients for the temperature
compensation are given in Table 7.
linearRH21Ctrue RHSOtt25TRH
SORH t1 t2
12 bit 0.01 0.00008
8 bit 0.01 0.00128
Table 7: Temperature compensation coefficients14
4.3 Temperature
The band-gap PTAT (Proportional To Absolute
Temperature) temperature sensor is very linear by design.
13 If wetted excessively (strong condensation of water on sensor surface),
sensor output signal can drop below 100%RH (even below 0%RH in some
cases), but the sensor will recover completely when water droplets
evaporate. The sensor is not damaged by water immersion or condensation.
14 Coefficients apply both to V3 as well as to V4 sensors.
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Use the following formula to convert digital readout (SOT)
to temperature value, with coefficients given in Table 8:
T21 SOddT
VDD d1 (°C) d1 (°F) SOT d2 (°C) d2 (°F)
5V -40.1 -40.2 14bit 0.01 0.018
4V -39.8 -39.6
12bit 0.04 0.072
3.5V -39.7 -39.5
3V -39.6 -39.3
2.5V -39.4 -38.9
Table 8: Temperature conversion coefficients15.
4.4 Dew Point
SHT1x is not measuring dew point directly, however dew
point can be derived from humidity and temperature
readings. Since humidity and temperature are both
measured on the same monolithic chip, the SHT1x allows
superb dew point measurements.
For dew point (Td) calculations there are various formulas
to be applied, most of them quite complicated. For the
temperature range of -40 50°C the following
approximation provides good accuracy with parameters
given in Table 9:
 
TT Tm
100%
RH
lnm
TT Tm
100%
RH
ln
TTRH,T
n
n
nd
Temperature Range Tn (°C) m
Above water, 0 – 50°C 243.12 17.62
Above ice, -40 – 0°C 272.62 22.46
Table 9: Parameters for dew point (Td) calculation.
Please note that “ln(…)” denotes the natural logarithm. For
RH and T the linearized and compensated values for
relative humidity and temperature shall be applied.
For more information on dew point calculation see
Application Note “Introduction to Humidity”.
5 Environmental Stability
If sensors are qualified for assemblies or devices, 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
15 Temperature coefficients have slightly been adjusted compared to datasheet
SHTxx version 3.01. Coefficients apply to V3 as well as V4 sensors.
enough dwell time for the measurement shall be granted.
For detailed information please consult Application Note
“Qualification Guide”.
The SHT1x 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 1016.
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.
Please contact Sensirion for detailed information.
Environment Standard Results17
HTSL 125°C, 1000 hours Within
specifications
TC -50°C - 125°C, 1000 cycles
Acc. JESD22-A104-C Within
specifications
UHST 130°C / 85%RH / ≈2.3bar,
96h Within
specifications
THU 85°C / 85%RH, 1000h Within
specifications
ESD immunity MIL STD 883E, method 3015
(Human Body Model at ±2kV) Qualified
Latch-up force current of ±100mA with
Tamb = 80°C, acc. JEDEC 17 Qualified
Table 10: Qualification tests: HTSL = High Temperature Storage
Lifetime, TC = Temperature Cycles, UHST = Unbiased Highly
accelerated Stress Test, THB = Temperature Humidity Unbiased
6 Packaging
6.1 Packaging type
SHT1x are supplied in a surface mountable LCC
(Leadless Chip Carrier) type package. The sensor housing
consists of a Liquid Crystal Polymer (LCP) cap with epoxy
glob top on a standard 0.8mm FR4 substrate. The device
is fully RoHS and WEEE compliant it is free of Pb, Cd,
Hg, Cr(6+), PBB and PBDE.
Device size is 7.47 x 4.93 x 2.5 mm (0.29 x 0.19 x 0.1
inch), see Figure 1, weight is 100 mg.
6.2 Traceability Information
All SHT1x are marked with an alphanumeric, three digit
code on the chip cap (for reference: V3 sensors were
labeled with numeric codes) see A5Z on Figure 1. The
lot numbers allow full traceability through production,
16 Sensor operation temperature range is -40 to 105°C according to AEC-Q100
temperature grade 2.
17 According to accuracy and long term drift specification given on Page 2.
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calibration and testing. No information can be derived from
the code directly; respective data is stored at Sensirion
and is provided upon request.
Labels on the reels are displayed in Figures 19 and 20,
they both give traceability information.
Figure 19: First label on reel: XX = Sensor Type (11 for SHT11),
NN = Chip Version (04 for V4), Y = last digit of year, RRR =
number of sensors on reel divided by 10 (200 for 2000 units),
TTTTT = Traceability Code.
Figure 20: Second label on reel: For Device Type and Part
Order Number please refer to Table 12, Delivery Date (also
Date Code) is date of packaging of sensors (DD = day, MM =
month, YYYY = year), CCCC = Sensirion order number.
6.3 Shipping Package
SHT1x are shipped in 12mm tape at 100pcs, 400pcs and
2000pcs for details see Figure 21 and Table 11. Reels
are individually labeled with barcode and human readable
labels.
Sensor Type Packaging Quantity Order Number
SHT10 Tape & Reel 2000 1-100218-04
Tape & Reel 100 1-100051-04
Tape & Reel 400 1-100098-04
SHT11 Tape & Reel 2000 1-100524-04
Tape & Reel 100 1-100085-04
SHT15 Tape & Reel 400 1-100093-04
Table 11: Packaging types per sensor type.
Dimensions of packaging tape are given in Figure 21. All
tapes have a minimum of 480mm empty leader tape (first
pockets of the tape) and a minimum of 300mm empty
trailer tape (last pockets of the tape).
Figure 21: Tape configuration and unit orientation within tape,
dimensions in mm (1mm = 0.039inch). The leader tape is at the
right side of the figure while the trailer tape is to the left
(direction of unreeling).
Device Type: 1-100PPP-NN
Description: Humidity & Temperature Sensor
SHTxx
Part Order No. 1-100PPP-NN or Customer Number
Date of Delivery: DD.MM.YYYY
Order Code: 46CCCC / 0
Lot No.: XX0-NN-YRRRTTTTT
Quantity: RRRR
RoHS: Compliant
Lot No.
2.00 ± 0.05
12.00
Ø1.50 MIN
Ø1.50 MIN
1
.00
1.75
± 0.
10
5.50
± 0.
05
12.0
± 0.
3
R0.5 TYP
8.20
2.80
0.30
± 0.05
R0.3 MAX
5.80
A5Z
11
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Datasheet SHT1x
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Revision History
Date Version Page(s) Changes
July 2008 4.0 1 – 11 New release, rework of datasheet
September 2008 4.1 3, 4 Adjustment of normal operating range and recommendation for antistatic bag
April 2009 4.2 2, 7 Amended foot note 2, communication diagram updated (Figure 17).
May 2010 4.3 1 – 11 Various errors corrected and additional information given (ask for change protocol).
Important Notices
Warning, Personal Injury
Do not use this product as safety or emergency stop devices or in
any other application where failure of the product could result in
personal injury. Do not use this product for applications other
than its intended and authorized use. Before installing, handling,
using or servicing this product, please consult the data sheet and
application notes. Failure to comply with these instructions could
result in death or serious injury.
If the Buyer shall purchase or use SENSIRION products for any
unintended or unauthorized application, Buyer shall defend, indemnify
and hold harmless SENSIRION and its officers, employees,
subsidiaries, affiliates and distributors against all claims, costs,
damages and expenses, and reasonable attorney fees arising out of,
directly or indirectly, any claim of personal injury or death associated
with such unintended or unauthorized use, even if SENSIRION shall be
allegedly negligent with respect to the design or the manufacture of the
product.
ESD Precautions
The inherent design of this component causes it to be sensitive to
electrostatic discharge (ESD). To prevent ESD-induced damage and/or
degradation, take customary and statutory ESD precautions when
handling this product.
See application note “ESD, Latchup and EMC” for more information.
Warranty
SENSIRION warrants solely to the original purchaser of this product for
a period of 12 months (one year) from the date of delivery that this
product shall be of the quality, material and workmanship defined in
SENSIRION’s published specifications of the product. Within such
period, if proven to be defective, SENSIRION shall repair and/or
replace this product, in SENSIRION’s discretion, free of charge to the
Buyer, provided that:
notice in writing describing the defects shall be given to
SENSIRION within fourteen (14) days after their appearance;
such defects shall be found, to SENSIRION’s reasonable
satisfaction, to have arisen from SENSIRION’s faulty design,
material, or workmanship;
the defective product shall be returned to SENSIRION’s factory at
the Buyer’s expense; and
the warranty period for any repaired or replaced product shall be
limited to the unexpired portion of the original period.
This warranty does not apply to any equipment which has not been
installed and used within the specifications recommended by
SENSIRION for the intended and proper use of the equipment.
EXCEPT FOR THE WARRANTIES EXPRESSLY SET FORTH
HEREIN, SENSIRION MAKES NO WARRANTIES, EITHER EXPRESS
OR IMPLIED, WITH RESPECT TO THE PRODUCT. ANY AND ALL
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.
SENSIRION does not assume any liability arising out of any application
or use of any product or circuit and specifically disclaims any and all
liability, including without limitation consequential or incidental
damages. All operating parameters, including without limitation
recommended parameters, must be validated for each customer’s
applications by customer’s technical experts. Recommended
parameters can and do vary in different applications.
SENSIRION reserves the right, without further notice, (i) to change the
product specifications and/or the information in this document and (ii) to
improve reliability, functions and design of this product.
Copyright© 2009, SENSIRION.
CMOSens® is a trademark of Sensirion
All rights reserved
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