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
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).
Dimensions
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 (Leadless
Chip Carrier) which is approved for standard reflow
soldering processes. The same sensor is also available
with pins (SHT7x) or on flex print (SHTA1).
Sensor Chip
SHT1x V4 – for which this datasheet applies – features a
version 4 Silicon sensor chip. Besides a humidity and a
temperature sensor 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 “A5Z” code 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 of the sensor
there is an evaluation kit
EK-H2
available including sensor,
hard and software to interface with a computer.
For more sophisticated and demanding measurements a
multi port evaluation kit
EK-H3
is available which allows for
parallel application of up to 20 sensors.
5.2
±0.2
2.2
MAX
2.6
MAX
0.8
±0.1
0.95
±0.1
1.5
±0.2
2.0
±0.1
1.5
±0.1
sensor opening
0.6
±0.1
2.5
±0.1
NC
4.2
±0.1
1.27
±0.05
1
2
3
1.83
±0.05
4
NC
NC
7.47
±0.05
A5Z
NC
NC
NC
11
3.3
±0.1
4.93
±0.05
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.
Version 4.0 – July 2008
Datasheet SHT1x
Sensor Performance
Relative Humidity
123
Parameter
Resolution
1
Accuracy
2
SHT10
Accuracy
2
SHT11
Accuracy
2
SHT15
Repeatability
Replacement
Hysteresis
Nonlinearity
raw data
linearized
0
< 0.5
typical
maximal
typical
maximal
typical
maximal
Condition
min
0.4
8
typ
0.05
12
max
0.05
12
Units
%RH
bit
%RH
%RH
%RH
%RH
%RH
%RH
%RH
s
100 %RH
%RH/yr
Temperature
45
Parameter
Resolution
1
Accuracy
2
SHT10
Accuracy
2
SHT11
Accuracy
2
SHT15
Repeatability
Replacement
Operating Range
Response Time
6
τ
(63%)
Long term drift
typical
maximal
typical
maximal
typical
maximal
Condition
min
0.04
12
typ
0.01
14
max
0.01
14
Units
°C
bit
°C
°C
°C
±4.5
see Figure 2
±3.0
see Figure 2
±2.0
see Figure 2
±0.1
fully interchangeable
±1
±3
<<1
8
±0.5
see Figure 3
±0.4
see Figure 3
±0.3
see Figure 3
Response time
3
τ
(63%)
Operating Range
Long term drift
4
normal
± 10
±8
∆
RH (%RH)
°C
±0.1
fully interchangeable
-40
123.8 °C
-40
254.9 °F
5
30
s
< 0.04
°C/yr
± 3.0
± 2.5
± 2.0
SHT10
SHT10
SHT11
∆
T (°C)
SHT15
±6
±4
±2
±0
0
10
20
30 40 50 60 70
Relative Humidity (%RH)
80
90
100
SHT11
± 1.5
± 1.0
± 0.5
± 0.0
-40
-20
0
20
40
60
Temperature (°C)
SHT15
80
100
Figure 2:
Maximal RH-accuracy at 25°C per sensor type.
Figure 3:
Maximal T-accuracy per sensor type.
Electrical and General Items
Parameter
Source Voltage
Power
Consumption
5
Communication
Storage
typ max Units
3.3
5.5
V
sleep
2
5
W
measuring
3
mW
average
150
W
digital 2-wire interface, see Communication
10 – 50°C (0 – 125°C peak), 20 – 60%RH
Condition
min
2.4
Packaging Information
Sensor Type
SHT10
SHT11
Packaging
Tape & Reel
Tape & Reel
Tape & Reel
Tape & Reel
Tape & Reel
Tape & Reel
Quantity
2000
100
400
2000
100
400
Order Number
1-100218-04
1-100051-04
1-100098-04
1-100524-04
1-100085-04
1-100093-04
SHT15
4
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 non-linearity.
3
Time for reaching 63% of a step function, valid at 25°C and 1 m/s airflow.
Value may be higher in environments with high contents of volatile organic
compounds. See Section 1.3 of Users Guide.
5
Values for VDD=5.5V 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.
www.sensirion.com
Version 4.0 – July 2008
2/11
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 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.
Relative Humidity (%)
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.
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
the soldering pads shall be sealed 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.
2.47
1.97
1.38
1.07
Ø0.60
1.27 1.27 1.27
100
60
40
20
0
-40
Max. Range
80
Normal
Range
-20
0
20
40
60
Temperature (°C)
80
100
120
7.47
0.47
0.80
Figure 4:
Operating Conditions
No copper in this field
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-020C with peak
temperatures at 260°C during up to 40sec including Pb-
free assembly in IR/Convection reflow ovens.
T
P
t
P
Figure 6:
Rear side electrodes of sensor, view from top side.
1.27 1.27 1.27
1.8
4.61
Temperature
T
L
T
S
(max)
t
L
0.8
1.8
3.48
7.08
preheating
critical zone
Time
Figure 7:
Recommended footprint for SHT1x. Values in mm.
Figure 5:
Soldering profile according to JEDEC standard. T
P
<=
260°C and t
P
< 40sec for Pb-free assembly. T
L
< 220°C and t
L
<
150sec. Ramp-up/down speeds shall be < 5°C/sec.
For soldering in Vapor Phase Reflow (VPR) ovens the
peak conditions are limited to T
P
< 233°C during t
P
<
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°C
7
.
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
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).
7
233°C = 451°F, 260°C = 500°F, 350°C = 662°F
Version 4.0 – July 2008
7.50
Datasheet SHT1x
For sensors that have been removed from the original
packaging we recommend to stored them in ESD bags
made of PE-HD
8
.
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:
Re-Hydration:
100 – 105°C at < 5%RH for 10h
20 – 30°C at ~ 75%RH for 12h
9
.
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.
membrane
o-ring
housing
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).
SHT1x
PCB
Melted plastic pin
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): 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
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.
4/11
A5Z
11
Figure 8:
Top view of example of mounted SHT1x with slits
milled into PCB to minimize heat transfer.
Furthermore, there are self-heating effects in case the
measurement frequency is too high. Please refer to
Section 3.3 for detailed information.
8
9
For example, please check www.sirel.ch
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
www.sensirion.com
Version 4.0 – July 2008
Datasheet SHT1x
Capacitor should be placed as close to the sensor as
possible. Please see the Application Note “ESD, Latchup
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 T
amb
= 80°C according to JEDEC78A. See
Application Note “ESD, Latchup and EMC” for more
information.
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 DATA may be changed. For safe
communication DATA valid shall be extended T
SU
and T
HO
before the rising and after the falling edge of SCK,
respectively – see Figure 11. For reading data from the
sensor, DATA is valid T
V
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. 10k ) 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. 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.
Parameter
Conditions
min
Power supply DC
10
2.4
measuring
Supply current
average
11
2
sleep
Low level output
I
OL
< 4 mA
0
voltage
High level output
R
P
< 25 k
90%
voltage
Low level input
Negative going 0%
voltage
High level input
Positive going 80%
voltage
Input current on
pads
on
Output current
Tri-stated (off)
typ
3.3
0.55
28
0.3
max Units
5.5
V
1
mA
A
1.5
A
250
mV
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
NC
1
2
3
4
NC
NC
NC
NC
NC
A5Z
11
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 capacitor – see Figure 10.
The serial interface of the SHT1x is optimized for sensor
readout and effective power consumption. The sensor
cannot be addressed by I
2
C protocol, however, the sensor
can be connected to an I
2
C bus without interference with
other devices connected to the bus. The controller must
switch between the protocols.
VDD
R
P
10k
GND
100% VDD
20% VDD
100% VDD
1
4
20
A
mA
A
SHT1x
Micro-
Controller
(Master)
DATA
SCK
VDD
100nF
A5Z
11
(Slave)
GND
10
2.4 – 5.5V
Figure 10:
Typical application circuit, including pull up resistor
R
P
and decoupling of VDD and GND by a capacitor.
Table 2:
SHT1x DC characteristics. R
P
stands for pull up
resistor, while I
OL
is low level output current.
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.
10
Recommended voltage supply for highest accuracy is 3.3V, due to sensor
calibration.
11
Minimum value with one measurement of 8 bit accuracy without OTP reload
per second, typical value with one measurement of 12bit accuracy per
second.
www.sensirion.com
Version 4.0 – July 2008
5/11
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