www.sensirion.com March 2017 - Version 4 1/20
Datasheet SHT3x-DIS
Humidity and Temperature Sensor
Fully calibrated, linearized, and temperature
compensated digital output
Wide supply voltage range, from 2.4 V to 5.5 V
I2C Interface with communication speeds up to 1
MHz and two user selectable addresses
Typical accuracy of 1.5 %RH and 0.1 °C for
SHT35
Very fast start-up and measurement time
Tiny 8-Pin DFN package
Product Summary
SHT3x-DIS is the next generation of Sensirion’s
temperature and humidity sensors. It builds on a new
CMOSens® sensor chip that is at the heart of Sensirion’s
new humidity and temperature platform. The SHT3x-DIS
has increased intelligence, reliability and improved
accuracy specifications compared to its predecessor. Its
functionality includes enhanced signal processing, two
distinctive and user selectable I2C addresses and
communication speeds of up to 1 MHz. The DFN
package has a footprint of 2.5 x 2.5 mm2 while keeping
a height of 0.9 mm. This allows for integration of the
SHT3x-DIS into a great variety of applications.
Additionally, the wide supply voltage range of 2.4 V to
5.5 V guarantees compatibility with diverse assembly
situations. All in all, the SHT3x-DIS incorporates 15
years of knowledge of Sensirion, the leader in the
humidity sensor industry.
Benefits of Sensirion’s CMOSens® Technology
High reliability and long-term stability
Industry-proven technology with a track record of
more than 15 years
Designed for mass production
High process capability
High signal-to-noise ratio
Content
1 Sensor Performance............................................. 2
2 Specifications ....................................................... 6
3 Pin Assignment .................................................... 8
4 Operation and Communication ............................. 9
5 Packaging ........................................................... 15
6 Shipping Package .............................................. 17
7 Quality ................................................................ 18
8 Ordering Information........................................... 18
Figure 1 Functional block diagram of the SHT3x-DIS. The
sensor signals for humidity and temperature are factory
calibrated, linearized and compensated for temperature
and supply voltage dependencies.
nRESET
AlertSDA SCLADDR
Power on
Reset
Alert Logic
RESET
Digital Interface
RH Sensor T Sensor
Data processing
& Linearization
ADCADC
Calibration
Memory
VSS
VDD
VSS
VDD
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 2/20
1 Sensor Performance
Humidity Sensor Specification
Parameter
Condition
Units
SHT30 Accuracy tolerance1
Typ.
%RH
Max.
-
SHT31 Accuracy tolerance1
Typ.
%RH
Max.
-
SHT35 Accuracy tolerance1
Typ.
%RH
Max.
-
Repeatability2
Low
%RH
Medium
%RH
High
%RH
Resolution
Typ.
%RH
Hysteresis
at 25°C
%RH
Specified range3
extended4
%RH
Response time5
63%
s
Long-term drift
Typ.7
%RH/yr
Table 1 Humidity sensor specification.
Temperature Sensor Specification
Parameter
Condition
Units
SHT30 Accuracy tolerance1
typ., 0°C to 65°C
°C
SHT31 Accuracy tolerance1
typ., 0°C to 90°C
°C
SHT35 Accuracy tolerance1
typ., 20°C to 60°C
°C
Repeatability2
Low
°C
Medium
°C
High
°C
Resolution
Typ.
°C
Specified Range
-
°C
Response time 8
63%
s
Long Term Drift
max
°C/yr
Table 2 Temperature sensor specification.
1
For definition of typical and maximum accuracy tolerance, please refer to the document “Sensirion Humidity Sensor Specification Statement”.
2
The stated repeatability is 3 times the standard deviation (3σ) of multiple consecutive measurements at the stated repeatability and at constant ambient conditions. It
is a measure for the noise on the physical sensor output. Different measurement modes allow for high/medium/low repeatability.
3
Specified range refers to the range for which the humidity or temperature sensor specification is guaranteed.
4
For details about recommended humidity and temperature operating range, please refer to section 1.1.
5
Time for achieving 63% of a humidity step function, valid at 25°C and 1m/s airflow. Humidity response time in the application depends on the design-in of the sensor.
6
With activated ART function (see section 4.7) the response time can be improved by a factor of 2.
7
Typical value for operation in normal RH/T operating range, see section 1.1. Maximum value is < 0.5 %RH/yr. Higher drift values might occur due to contaminant
environments with vaporized solvents, out-gassing tapes, adhesives, packaging materials, etc. For more details please refer to Handling Instructions.
8
Temperature response times strongly depend on the type of heat exchange, the available sensor surface and the design environment of the sensor in the final
application.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 3/20
Humidity Sensor Performance Graphs
Figure 2 Tolerance of RH at 25°C for SHT30.
Figure 3 Tolerance of RH at 25°C for SHT31.
Figure 4 Tolerance of RH at 25°C for SHT35.
±0
±2
±4
±6
±8
010 20 30 40 50 60 70 80 90 100
Relative Humidity (%RH)
SHT30
maximal tolerance
typical tolerance
DRH (%RH)
±0
±2
±4
±6
±8
010 20 30 40 50 60 70 80 90 100
Relative Humidity (%RH)
SHT31
maximal tolerance
typical tolerance
DRH (%RH)
±0
±2
±4
±6
010 20 30 40 50 60 70 80 90 100
Relative Humidity (%RH)
SHT35
maximal tolerance
typical tolerance
DRH (%RH)
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 4/20
SHT30
SHT31
RH (%RH)
100
±4
±4
±4
±4
±4
±4
±4
±4
90
±3
±3
±3
±3
±3
±3
±3
±3
80
±2
±2
±2
±2
±2
±2
±2
±2
70
±2
±2
±2
±2
±2
±2
±2
±2
60
±2
±2
±2
±3
±2
±2
±2
±2
50
±2
±2
±2
±2
±2
±2
±2
±2
40
±2
±2
±2
±2
±2
±2
±2
±2
30
±2
±2
±2
±2
±2
±2
±2
±2
20
±2
±2
±2
±2
±2
±2
±2
±2
10
±3
±3
±3
±3
±3
±3
±3
±3
0
±4
±4
±4
±4
±4
±4
±4
±4
0
10
20
30
40
50
60
70
80
Temperature (°C)
RH (%RH)
100
±2
±2
±2
±2
±2
±2
±2
±2
±2
90
±2
±2
±2
±2
±2
±2
±2
±2
±2
80
±2
±2
±2
±2
±2
±2
±2
±2
±2
70
±2
±2
±2
±2
±2
±2
±2
±2
±2
60
±2
±2
±2
±2
±2
±2
±2
±2
±2
50
±2
±2
±2
±2
±2
±2
±2
±2
±2
40
±2
±2
±2
±2
±2
±2
±2
±2
±2
30
±2
±2
±2
±2
±2
±2
±2
±2
±2
20
±2
±2
±2
±2
±2
±2
±2
±2
±2
10
±2
±2
±2
±2
±2
±2
±2
±2
±2
0
±2
±2
±2
±2
±2
±2
±2
±2
±2
0
10
20
30
40
50
60
70
80
Temperature (°C)
Figure 5 Typical tolerance of RH over T for SHT30.
Figure 6 Typical tolerance of RH over T for SHT31.
SHT35
RH (%RH)
100
±2
±2
±2
±2
±2
±2
±2
±2
±2
90
±2
±2
±2
±2
±2
±2
±2
±2
±2
80
±2
±2
±2
±2
70
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
±2
60
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
±2
50
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
±2
40
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
30
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
20
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
10
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
0
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±1.5
±2
0
10
20
30
40
50
60
70
80
Temperature (°C)
Figure 7 Typical tolerance of RH over T for SHT35.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 5/20
Temperature Sensor Performance Graphs
SHT30
SHT31
Figure 8 Temperature accuracy of the SHT30 sensor.
Figure 9 Temperature accuracy of the SHT31 sensor.
SHT35
Figure 10 Temperature accuracy of the SHT35 sensor.
±0.0
±0.5
±1.0
±1.5
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
maximal tolerance
typical tolerance
DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)
±0.0
±0.5
±1.0
±1.5
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
maximal tolerance
typical tolerance
DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)
±0.0
±0.5
±1.0
±1.5
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
maximal tolerance
typical tolerance
DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)DT (°C)
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 6/20
1.1 Recommended Operating Condition
The sensor shows best performance when operated within recommended normal temperature and humidity range of 5 °C
– 60 °C and 20 %RH – 80 %RH, respectively. Long-term exposure to conditions outside normal range, especially at high
humidity, may temporarily offset the RH signal (e.g. +3%RH after 60h kept at >80%RH). After returning into the normal
temperature and humidity range the sensor will slowly come back to calibration state by itself. Prolonged exposure to
extreme conditions may accelerate ageing. To ensure stable operation of the humidity sensor, the conditions described in
the document “SHTxx Assembly of SMD Packages”, section “Storage and Handling Instructions” regarding exposure to
volatile organic compounds have to be met. Please note as well that this does apply not only to transportation and
manufacturing, but also to operation of the SHT3x-DIS.
2 Specifications
2.1 Electrical Specifications
Parameter
Symbol
Condition
Min.
Typ.
Max.
Units
Comments
Supply voltage
VDD
2.4
3.3
5.5
V
Power-up/down level
VPOR
2.1
2.3
2.4
V
Slew rate change of the
supply voltage
VDD,slew
-
-
20
V/ms
Voltage changes on the
VDD line between
VDD,min and VDD,max
should be slower than
the maximum slew rate;
faster slew rates may
lead to reset;
Supply current
IDD
idle state
(single shot mode)
-
0.2
2.0
A
Current when sensor is
not performing a
measurement during
single shot mode
idle state
(periodic data
acquisition mode)
-
45
-
A
Current when sensor is
not performing a
measurement during
periodic data acquisition
mode
Measuring
-
800
1500
A
Current consumption
while sensor is
measuring
Average
-
2
-
A
Current consumption
(operation with one
measurement per
second at lowest
repeatability, single shot
mode)
Alert Output driving
strength
IOH
1.5x VDD
mA
See also section 3.5
Heater power
PHeater
Heater running
4.5
-
33
mW
Depending on the
supply voltage
Table 3 Electrical specifications, valid at 25°C.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 7/20
2.2 Timing Specification for the Sensor System
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Comments
Power-up time
tPU
After hard reset,
VDD ≥ VPOR
-
0.5
1
ms
Time between VDD reaching
VPOR and sensor entering idle
state
Soft reset time
tSR
After soft reset.
-
0.5
1
ms
Time between ACK of soft
reset command and sensor
entering idle state
Duration of reset pulse
tRESETN
1
-
-
µs
See section 3.6
Measurement duration
tMEAS,l
Low repeatability
-
2.5
4
ms
The three repeatability modes
differ with respect to
measurement duration, noise
level and energy consumption.
tMEAS,m
Medium repeatability
-
4.5
6
ms
tMEAS,h
High repeatability
-
12.5
15
ms
Table 4 System timing specification, valid from -40 °C to 125 °C and 2.4 V to 5.5 V.
2.3 Absolute Minimum and Maximum Ratings
Stress levels beyond those listed in Table 5 may cause permanent damage to the device or affect the reliability of the
sensor. These are stress ratings only and functional operation of the device at these conditions is not guaranteed.
Parameter
Rating
Units
Supply voltage VDD
-0.3 to 6
V
Max Voltage on pins (pin 1 (SDA); pin 2 (ADDR); pin 3 (ALERT); pin 4 (SCL); pin 6
(nRESET))
-0.3 to VDD+0.3
V
Input current on any pin
±100
mA
Operating temperature range
-40 to 125
°C
Storage temperature range
-40 to 150
°C
ESD HBM (human body model)9
4
kV
ESD CDM (charge device model)10
750
V
Table 5 Minimum and maximum ratings; voltages may only be applied for short time periods.
9
According to ANSI/ESDA/JEDEC JS-001-2014; AEC-Q100-002.
10
According to ANSI/ESD S5.3.1-2009; AEC-Q100-011.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 8/20
3 Pin Assignment
The SHT3x-DIS comes in a tiny 8-pin DFN package –
see Table 6.
Pin
Name
Comments
1
SDA
Serial data; input / output
2
ADDR
Address pin; input; connect to either
logic high or low, do not leave floating
3
ALERT
Indicates alarm condition; output; must
be left floating if unused
4
SCL
Serial clock; input / output
5
VDD
Supply voltage; input
6
nRESET
Reset pin active low; input; if not used it
is recommended to be left floating; can
be connected to VDD with a series
resistor of R ≥2 kΩ
7
R
No electrical function; to be connected
to VSS
8
VSS
Ground
Table 6 SHT3x-DIS pin assignment (transparent top view).
Dashed lines are only visible if viewed from below. The die
pad is internally connected to VSS.
3.1 Power Pins (VDD, VSS)
The electrical specifications of the SHT3x-DIS are shown
in Table 3. The power supply pins must be decoupled
with a 100 nF capacitor that shall be placed as close to
the sensor as possible – see Figure 11 for a typical
application circuit.
3.2 Serial Clock and Serial Data (SCL, SDA)
SCL is used to synchronize the communication between
microcontroller and the sensor. The clock frequency can
be freely chosen between 0 to 1000 kHz. Commands
with clock stretching according to I2C Standard
11
are
supported.
The SDA pin is used to transfer data to and from the
sensor. Communication with frequencies up to 400 kHz
must meet the I2C Fast Mode11 standard.
11
http://www.nxp.com/documents/user_manual/UM10204.pdf
Communication frequencies up to 1 Mhz are supported
following the specifications given in Table 20.
Both SCL and SDA lines are open-drain I/Os with diodes
to VDD and VSS. They should be connected to external
pull-up resistors (please refer to Figure 11). A device on
the I2C bus must only drive a line to ground. The external
pull-up resistors (e.g. Rp=10 kΩ) are required to pull the
signal high. For dimensioning resistor sizes please take
bus capacity and communication frequency into account
(see for example Section 7.1 of NXPs I2C Manual for
more details11). It should be noted that pull-up resistors
may be included in I/O circuits of microcontrollers. It is
recommended to wire the sensor according to the
application circuit as shown in Figure 11.
Figure 11 Typical application circuit. Please note that the
positioning of the pins does not reflect the position on the
real sensor. This is shown in Table 6.
3.3 Die Pad (center pad)
The die pad or center pad is visible from below and
located in the center of the package. It is electrically
connected to VSS. Hence electrical considerations do
not impose constraints on the wiring of the die pad.
However, due to mechanical reasons it is recommended
to solder the center pad to the PCB. For more
information on design-in, please refer to the document
“SHTxx Design Guide”.
3.4 ADDR Pin
Through the appropriate wiring of the ADDR pin the I2C
address can be selected (see Table 7 for the respective
addresses). The ADDR pin can either be connected to
logic high or logic low. The address of the sensor can be
changed dynamically during operation by switching the
level on the ADDR pin. The only constraint is that the
level has to stay constant starting from the I2C start
condition until the communication is finished. This allows
to connect more than two SHT3x-DIS onto the same bus.
1
2
3
45
8
7
6
VDD
RR
PP
100nF
ADDR(2)
ALERT(3)
die
pad R(7)
SDA(1)
SCL(4)
VDD(5)
VSS(8)
nRESET(6)
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 9/20
The dynamical switching requires individual ADDR lines
to the sensors.
Please note that the I2C address is represented through
the 7 MSBs of the I2C read or write header. The LSB
switches between read or write header. The wiring for
the default address is shown in Table 7 and Figure 11.
The ADDR pin must not be left floating. Please note that
only the 7 MSBs of the I2C Read/Write header constitute
the I2C Address.
SHT3x-DIS
I2C Address in Hex.
representation
Condition
I2C address A
0x44 (default)
ADDR (pin 2)
connected to logic
low
I2C address B
0x45
ADDR (pin 2)
connected to logic
high
Table 7 I2C device addresses.
3.5 ALERT Pin
The alert pin may be used to connect to the interrupt pin
of a microcontroller. The output of the pin depends on
the value of the RH/T reading relative to programmable
limits. Its function is explained in a separate application
note. If not used, this pin must be left floating. The pin
switches high, when alert conditions are met. The
maximum driving loads are listed in Table 3. Be aware
that self-heating might occur, depending on the amount
of current that flows. Self-heating can be prevented if the
Alert Pin is only used to switch a transistor.
3.6 nRESET Pin
The nReset pin may be used to generate a reset of the
sensor. A minimum pulse duration of 1 µs is required to
reliably trigger a reset of the sensor. Its function is
explained in more detail in section 4. If not used it is
recommended to leave the pin floating or to connect it to
VDD with a series resistor of R ≥2 kΩ. However, the
nRESET pin is internally connected to VDD with a pull
up resistor of R = 50 kΩ (typ.).
4 Operation and Communication
The SHT3x-DIS supports I2C fast mode (and
frequencies up to 1000 kHz). Clock stretching can be
enabled and disabled through the appropriate user
command. For detailed information on the I2C protocol,
refer to NXP I2C-bus specification
12
.
All SHT3x-DIS commands and data are mapped to a 16-
bit address space. Additionally, data and commands are
12
http://www.nxp.com/documents/user_manual/UM10204.pdf
protected with a CRC checksum. This increases
communication reliability. The 16 bits commands to the
sensor already include a 3 bit CRC checksum. Data sent
from and received by the sensor is always succeeded by
an 8 bit CRC.
In write direction it is mandatory to transmit the
checksum, since the SHT3x-DIS only accepts data if it is
followed by the correct checksum. In read direction it is
left to the master to read and process the checksum.
4.1 Power-Up and Communication Start
The sensor starts powering-up after reaching the power-
up threshold voltage VPOR specified in Table 3. After
reaching this threshold voltage the sensor needs the
time tPU to enter idle state. Once the idle state is entered
it is ready to receive commands from the master
(microcontroller).
Each transmission sequence begins with a START
condition (S) and ends with a STOP condition (P) as
described in the I2C-bus specification. The stop
condition is optional. Whenever the sensor is powered
up, but not performing a measurement or
communicating, it automatically enters idle state for
energy saving. This idle state cannot be controlled by the
user.
4.2 Starting a Measurement
A measurement communication sequence consists of a
START condition, the I2C write header (7-bit I2C device
address plus 0 as the write bit) and a 16-bit
measurement command. The proper reception of each
byte is indicated by the sensor. It pulls the SDA pin low
(ACK bit) after the falling edge of the 8th SCL clock to
indicate the reception. A complete measurement cycle is
depicted in Table 8.
With the acknowledgement of the measurement
command, the SHT3x-DIS starts measuring humidity
and temperature.
4.3 Measurement Commands for Single Shot
Data Acquisition Mode
In this mode one issued measurement command
triggers the acquisition of one data pair. Each data pair
consists of one 16 bit temperature and one 16 bit
humidity value (in this order). During transmission each
data value is always followed by a CRC checksum, see
section 4.4.
In single shot mode different measurement commands
can be selected. The 16 bit commands are shown in
Table 8. They differ with respect to repeatability (low,
medium and high) and clock stretching (enabled or
disabled).
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 10/20
The repeatability setting influences the measurement
duration and thus the overall energy consumption of the
sensor. This is explained in section 2.
Condition
Hex. code
Repeatability
Clock
stretching
MSB
LSB
High
enabled
0x2C
06
Medium
0D
Low
10
High
disabled
0x24
00
Medium
0B
Low
16
e.g. 0x2C06: high repeatability measurement with clock
stretching enabled
Table 8 Measurement commands in single shot mode (Clear
blocks are controlled by the microcontroller, grey blocks by
the sensor).
4.4 Readout of Measurement Results for
Single Shot Mode
After the sensor has completed the measurement, the
master can read the measurement results (pair of RH&
T) by sending a START condition followed by an I2C
read header. The sensor will acknowledge the reception
of the read header and send two bytes of data
(temperature) followed by one byte CRC checksum and
another two bytes of data (relative humidity) followed by
one byte CRC checksum. Each byte must be
acknowledged by the microcontroller with an ACK
condition for the sensor to continue sending data. If the
sensor does not receive an ACK from the master after
any byte of data, it will not continue sending data.
The sensor will send the temperature value first and then
the relative humidity value. After having received the
checksum for the humidity value a NACK and stop
condition should be sent (see Table 8).
The I2C master can abort the read transfer with a NACK
condition after any data byte if it is not interested in
subsequent data, e.g. the CRC byte or the second
measurement result, in order to save time.
In case the user needs humidity and temperature data
but does not want to process CRC data, it is
recommended to read the two temperature bytes of data
with the CRC byte (without processing the CRC data);
after having read the two humidity bytes, the read
transfer can be aborted with a with a NACK.
No Clock Stretching
When a command without clock stretching has been
issued, the sensor responds to a read header with a not
acknowledge (NACK), if no data is present.
Clock Stretching
When a command with clock stretching has been issued,
the sensor responds to a read header with an ACK and
subsequently pulls down the SCL line. The SCL line is
pulled down until the measurement is complete. As soon
as the measurement is complete, the sensor releases
the SCL line and sends the measurement results.
4.5 Measurement Commands for Periodic
Data Acquisition Mode
In this mode one issued measurement command yields
a stream of data pairs. Each data pair consists of one 16
bit temperature and one 16 bit humidity value (in this
order).
In periodic mode different measurement commands can
be selected. The corresponding 16 bit commands are
shown in Table 9. They differ with respect to repeatability
(low, medium and high) and data acquisition frequency
(0.5, 1, 2, 4 & 10 measurements per second, mps). Clock
stretching cannot be selected in this mode.
The data acquisition frequency and the repeatability
setting influences the measurement duration and the
current consumption of the sensor. This is explained in
section 2 of this datasheet.
If a measurement command is issued, while the sensor
is busy with a measurement (measurement durations
see Table 4), it is recommended to issue a break
command first (see section 4.8). Upon reception of the
break command the sensor will finish the ongoing
measurement and enter the single shot mode.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 11/20
Condition
Hex. code
Repeatability
mps
MSB
LSB
High
0.5
0x20
32
Medium
24
Low
2F
High
1
0x21
30
Medium
26
Low
2D
High
2
0x22
36
Medium
20
Low
2B
High
4
0x23
34
Medium
22
Low
29
High
10
0x27
37
Medium
21
Low
2A
e.g. 0x2130: 1 high repeatability mps - measurement per
second
Table 9 Measurement commands for periodic data acquisition
mode (Clear blocks are controlled by the microcontroller, grey
blocks by the sensor). N.B.: At the highest mps setting self-
heating of the sensor might occur.
4.6 Readout of Measurement Results for
Periodic Mode
Transmission of the measurement data can be initiated
through the fetch data command shown in Table 10. If
no measurement data is present the I2C read header is
responded with a NACK (Bit 9 in Table 10) and the
communication stops. After the read out command fetch
data has been issued, the data memory is cleared, i.e.
no measurement data is present.
Command
Hex code
Fetch Data
0x E0 00
Table 10 Fetch Data command (Clear blocks are controlled
by the microcontroller, grey blocks by the sensor).
4.7 ART Command
The ART (accelerated response time) feature can be
activated by issuing the command in Table 11. After
issuing the ART command the sensor will start acquiring
data with a frequency of 4Hz.
The ART command is structurally similar to any other
command in Table 9. Hence section 4.5 applies for
starting a measurement, section 4.6 for reading out data
and section 4.8 for stopping the periodic data acquisition.
The ART feature can also be evaluated using the
Evaluation Kit EK-H5 from Sensirion.
Command
Hex Code
Periodic Measurement with
ART
0x2B32
Table 11 Command for a periodic data acquisition with
the ART feature (Clear blocks are controlled by the
microcontroller, grey blocks by the sensor).
4.8 Break command / Stop Periodic Data
Acquisition Mode
The periodic data acquisition mode can be stopped using
the break command shown in Table 12. It is
recommended to stop the periodic data acquisition prior
to sending another command (except Fetch Data
command) using the break command. Upon reception of
the break command the sensor enters the single shot
mode, after finishing the ongoing measurement. This
can take up to 15 ms, depending on the selected
repeatability.
Command
Hex Code
Break
0x3093
Table 12 Break command (Clear blocks are controlled by
the microcontroller, grey blocks by the sensor).
4.9 Reset
A system reset of the SHT3x-DIS can be generated
externally by issuing a command (soft reset) or by
sending a pulse to the dedicated reset pin (nReset pin).
Additionally, a system reset is generated internally
during power-up. During the reset procedure the sensor
will not process commands.
In order to achieve a full reset of the sensor without
removing the power supply, it is recommended to use the
nRESET pin of the SHT3x-DIS.
S
ACK
W
I2C Address
1 2 3 4 5 6 7 8 9
ACK
Command MSB
123456789
ACK
Command LSB
10 11 12 13 14 15 16 17 18
16-bit command
I2C write header
S
ACK
W
I2C Address
1 2 3 4 5 6 7 8 9
ACK
Command MSB
123456789
ACK
Command LSB
10 11 12 13 14 15 16 17 18
16-bit command
I2C write header
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 12/20
Interface Reset
If communication with the device is lost, the following
signal sequence will reset the serial interface: While
leaving SDA high, toggle SCL nine or more times. 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.
Soft Reset / Re-Initialization
The SHT3x-DIS provides a soft reset mechanism that
forces the system into a well-defined state without
removing the power supply. When the system is in idle
state the soft reset command can be sent to the SHT3x-
DIS. This triggers the sensor to reset its system
controller and reloads calibration data from the memory.
In order to start the soft reset procedure the command
as shown in Table 13 should be sent.
It is worth noting that the sensor reloads calibration data
prior to every measurement by default.
Command
Hex Code
Soft Reset
0x30A2
Table 13 Soft reset command (Clear blocks are controlled
by the microcontroller, grey blocks by the sensor).
Reset through General Call
Additionally, a reset of the sensor can also be generated
using the “general call” mode according to I2C-bus
specification12. This generates a reset which is
functionally identical to using the nReset pin. It is
important to understand that a reset generated in this
way is not device specific. All devices on the same I2C
bus that support the general call mode will perform a
reset. Additionally, this command only works when the
sensor is able to process I2C commands. The
appropriate command consists of two bytes and is
shown in Table 14.
Reset through the nReset Pin
Pulling the nReset pin low (see Table 6) generates a
reset similar to a hard reset. The nReset pin is internally
connected to VDD through a pull-up resistor and hence
active low. The nReset pin has to be pulled low for a
minimum of 1 µs to generate a reset of the sensor.
Command
Code
Address byte
0x00
Second byte
0x06
Reset command using the
general call address
0x0006
Table 14 Reset through the general call address (Clear
blocks are controlled by the microcontroller, grey blocks by
the sensor).
Hard Reset
A hard reset is achieved by switching the supply voltage
to the VDD Pin off and then on again. In order to prevent
powering the sensor over the ESD diodes, the voltage to
pins 1 (SDA), 4 (SCL) and 2 (ADDR) also needs to be
removed.
4.10 Heater
The SHT3x is equipped with an internal heater, which
is meant for plausibility checking only. The temperature
increase achieved by the heater depends on various
parameters and lies in the range of a few degrees
centigrade. It can be switched on and off by command,
see table below. The status is listed in the status register.
After a reset the heater is disabled (default condition).
Command
Hex Code
MSB
LSB
Heater Enable
0x30
6D
Heater Disabled
66
Table 15 Heater command (Clear blocks are controlled by
the microcontroller, grey blocks by the sensor).
4.11 Status Register
The status register contains information on the
operational status of the heater, the alert mode and on
the execution status of the last command and the last
write sequence. The command to read out the status
register is shown in Table 16 whereas a description of
the content can be found in Table 17.
S
ACK
General Call Address
1 2 3 4 5 6 7 8 9
ACK
Reset Command
1 2 3 4 5 6 7 8 9
General Call 1st byte General Call 2nd byte
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 13/20
Command
Hex code
Read Out of status register
0xF32D
Table 16 Command to read out the status register (Clear
blocks are controlled by the microcontroller, grey blocks by
the sensor).
Bit
Field description
Default
value
15
Alert pending status
'0': no pending alerts
'1': at least one pending alert
‘1’
14
Reserved
‘0’
13
Heater status
‘0’ : Heater OFF
‘1’ : Heater ON
‘0’
12
Reserved
‘0’
11
RH tracking alert
‘0’ : no alert
‘1’ . alert
‘0
10
T tracking alert
‘0’ : no alert
‘1’ . alert
‘0’
9:5
Reserved
‘xxxxx’
4
System reset detected
'0': no reset detected since last ‘clear
status register’ command
'1': reset detected (hard reset, soft reset
command or supply fail)
‘1’
3:2
Reserved
‘00’
1
Command status
'0': last command executed successfully
'1': last command not processed. It was
either invalid, failed the integrated
command checksum
‘0’
0
Write data checksum status
'0': checksum of last write transfer was
correct
'1': checksum of last write transfer failed
‘0’
Table 17 Description of the status register.
Clear Status Register
All flags (Bit 15, 11, 10, 4) in the status register can be
cleared (set to zero) by sending the command shown in
Table 18.
Command
Hex Code
Clear status register
0x 30 41
Table 18 Command to clear the status register (Clear
blocks are controlled by the microcontroller, grey blocks by
the sensor).
4.12 Checksum Calculation
The 8-bit CRC checksum transmitted after each data
word is generated by a CRC algorithm. Its properties are
displayed in Table 19. The CRC covers the contents of
the two previously transmitted data bytes. To calculate
the checksum only these two previously transmitted data
bytes are used.
Property
Value
Name
CRC-8
Width
8 bit
Protected data
read and/or write data
Polynomial
0x31 (x8 + x5 + x4 + 1)
Initialization
0xFF
Reflect input
False
Reflect output
False
Final XOR
0x00
Examples
CRC (0xBEEF) = 0x92
Table 19 I2C CRC properties.
4.13 Conversion of Signal Output
Measurement data is always transferred as 16-bit values
(unsigned integer). These values are already linearized
and compensated for temperature and supply voltage
effects. Converting those raw values into a physical
scale can be achieved using the following formulas.
Relative humidity conversion formula (result in %RH):
1
16
RH
2
S
100 RH
Temperature conversion formula (result in °C & °F):
1
1
16
T
16
T
2
S
315 49 F T
2
S
175 45 C T
SRH and ST denote the raw sensor output for humidity
and temperature, respectively. The formulas work only
correctly when SRH and ST are used in decimal
representation.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 14/20
4.14 Communication Timing
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Comments
SCL clock frequency
fSCL
0
-
1000
kHz
Hold time (repeated) START
condition
tHD;STA
After this period, the first
clock pulse is generated
0.24
-
-
µs
LOW period of the SCL
clock
tLOW
0.65
-
-
µs
HIGH period of the SCL
clock
tHIGH
0.26
-
-
µs
SDA hold time
tHD;DAT
0
-
250
ns
Transmitting data
0
-
-
ns
Receiving data
SDA set-up time
tSU;DAT
100
-
-
ns
SCL/SDA rise time
tR
-
-
300
ns
SCL/SDA fall time
tF
-
-
300
ns
SDA valid time
tVD;DAT
-
-
0.9
µs
Set-up time for a repeated
START condition
tSU;STA
0.6
-
-
µs
Set-up time for STOP
condition
tSU;STO
0.6
-
-
µs
Capacitive load on bus line
CB
-
-
400
pF
Low level input voltage
VIL
0
-
0.3xVDD
V
High level input voltage
VIH
0.7xVDD
-
1xVDD
V
Low level output voltage
VOL
3 mA sink current
-
-
0.66
V
Table 20 Communication timing specifications for I2C fm (fast mode), specifications are at 25°C and typical VDD. The numbers above
are values according to the I2C Specification (UM10204, Rev. 6, April 4, 2014).
Figure 12 Timing diagram for digital input/output pads. SDA directions are seen from the sensor. Bold SDA lines are
controlled by the sensor, plain SDA lines are controlled by the micro-controller. Note that SDA valid read time is triggered
by falling edge of preceding toggle.
SCL
70%
30%
tLOW
1/fSCL
tHIGH
tR
tF
SDA
70%
30%
tSU;DAT
tHD;DAT
DATA IN
tR
SDA
70%
30%
DATA OUT
tVD;DAT
tF
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 15/20
5 Packaging
SHT3x-DIS sensors are provided in an open-cavity DFN
package. DFN stands for dual flat no leads. The humidity
sensor opening is centered on the top side of the
package.
The sensor chip is made of silicon and is mounted to a
lead frame. The latter is made of Cu plated with
Ni/Pd/Au. Chip and lead frame are overmolded by an
epoxy-based mold compound leaving the central die pad
and I/O pins exposed for mechanical and electrical
connection. Please note that the side walls of the sensor
are diced and therefore these diced lead frame surfaces
are not covered with the respective plating.
The package (except for the humidity sensor opening)
follows JEDEC publication 95, design registration 4.20,
small scale plastic quad and dual inline, square and
rectangular, No-LEAD packages (with optional thermal
enhancements) small scale (QFN/SON), Issue D.01,
September 2009.
SHT3x-DIS has a Moisture Sensitivity Level (MSL) of 1,
according to IPC/JEDEC J-STD-020. At the same time,
it is recommended to further process the sensors within
1 year after date of delivery.
5.1 Traceability
All SHT3x-DIS sensors are laser marked for easy
identification and traceability. The marking on the sensor
top side consists of a pin-1 indicator and two lines of text.
The top line consist of the pin-1 indicator which is located
in the top left corner and the product name. The small
letter x stands for the accuracy class.
The bottom line consists of 6 letters. The first two digits
XY (=DI) describe the output mode. The third letter (A)
represents the manufacturing year (4 = 2014, 5 = 2015,
etc). The last three digits (BCD) 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.
If viewed from below pin 1 is indicated by triangular
shaped cut in the otherwise rectangular die pad. The
dimensions of the triangular cut are shown in Figure 14
through the labels T1 & T2.
Figure 13 Top view of the SHT3x-DIS illustrating the laser
marking.
SHT3x
XYABCD
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 16/20
5.2 Package Outline
Figure 14 Dimensional drawing of SHT3x-DIS sensor package
Parameter
Symbol
Min
Nom.
Max
Units
Comments
Package height
A
0.8
0.9
1
mm
Leadframe height
A3
-
0.2
-
mm
Pad width
b
0.2
0.25
0.3
mm
Package width
D
2.4
2.5
2.6
mm
Center pad length
D2
1
1.1
1.2
mm
Package length
E
2.4
2.5
2.6
mm
Center pad width
E2
1.7
1.8
1.9
mm
Pad pitch
e
-
0.5
mm
Pad length
L
0.25
0.35
0.45
mm
Max cavity
S
-
-
1.5
mm
Only as guidance. This value includes all tolerances,
including displacement tolerances. Typically the opening
will be smaller.
Center pad marking
T1xT2
-
0.3x45°
-
mm
indicates the position of pin 1
Table 21 Package outline.
5.3 Land Pattern
Figure 15 shows the land pattern. The land pattern is
understood to be the open metal areas on the PCB, onto
which the DFN pads are soldered.
The solder mask is understood to be the insulating layer
on top of the PCB covering the copper traces. It is
recommended to design the solder pads as a Non-
Solder Mask Defined (NSMD) type. For NSMD pads, the
solder mask opening should provide a 60 μm to 75 μm
design clearance between any copper pad and solder
mask. As the pad pitch is only 0.5 mm we recommend to
have one solder mask opening for all 4 I/O pads on one
side.
For solder paste printing it is recommended to use a
laser-cut, stainless steel stencil with electro-polished
trapezoidal walls and with 0.1 or 0.125 mm stencil
thickness. The length of the stencil apertures for the I/O
pads should be the same as the PCB pads. However,
the position of the stencil apertures should have an offset
of 0.1 mm away from the center of the package. The die
pad aperture should cover about 70 – 90 % of the die
pad area –thus it should have a size of about 0.9 mm x
1.6 mm.
For information on the soldering process and further
recommendation on the assembly process please
consult the Application Note
HT_AN_SHTxx_Assembly_of_SMD_Packages , which
can be found on the Sensirion webpage.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 17/20
Figure 15 Recommended metal land pattern (left) and stencil apertures (right) for SHT3x-DIS. The dashed lines represent the outer
dimension of the DFN package. The PCB pads (left) and stencil apertures (right) are indicated through the shaded areas.
6 Shipping Package
Figure 16 Technical drawing of the packaging tape with sensor orientation in tape. Header tape is to the right and trailer tape to the
left on this drawing. Dimensions are given in millimeters.
Recommended Land Pattern Recommended Stencil Aperture
1.7
0.25
0.55 1
0.5 0.5 0.5
2.35
0.2 0.9
1.6
0.5 0.5 0.5
0.25
0.55
2.55
0.3
TOLERANCES - UNLESS
NOTED 1PL ±.2 2PL ±.10
A = 2.75
B = 2.75
K = 1.20
0
0
0
NOTES:
1. 10 SPROCKET HOLE PITCH CUMULATIVE TOLERANCE ±0.2
2. POCKET POSITION RELATIVE TO SPROCKET HOLE MEASURED
AS TRUE POSITION OF POCKET, NOT POCKET HOLE
3. A0 AND B0 ARE CALCULATED ON A PLANE AT A DISTANCE "R"
ABOVE THE BOTTOM OF THE POCKET
A0
K0
B0
R 0.25 TYP.
SECTION A - A
0.30 ±.05
A
R 0.2 MAX.
0.30 ±.05
2.00 ±.05 SEE Note 2 4.00
4.00 SEE Note 1
Ø1.5 +.1 /-0.0
Ø1.00 MIN 1.75 ±.1
12.0 +0.3/-0.1
5.50 ±.05
SEE NOTE 2
A
B
DETAIL B
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 18/20
7 Quality
Qualification of the SHT3x-DIS is performed based
on the AEC Q 100 qualification test method.
7.1 Material Contents
The device is fully RoHS and WEEE compliant, e.g.
free of Pb, Cd, and Hg.
8 Ordering Information
The SHT3x-DIS can be ordered in tape and reel
packaging with different sizes, see Table 22. The
reels are sealed into antistatic ESD bags. The
document “SHT3x shipping package” that shows the
details about the shipping package is available upon
request.
Name
Quantity
Order Number
SHT30-DIS-B2.5kS
2500
1-101400-01
SHT30-DIS-B10kS
10000
1-101173-01
SHT31-DIS-B2.5kS
2500
1-101386-01
SHT31-DIS-B10kS
10000
1-101147-01
SHT35-DIS-B2.5kS
2500
1-101388-01
SHT35-DIS-B10kS
10000
1-101479-01
Table 22 SHT3x-DIS ordering options.
9 Further Information
For more in-depth information on the SHT3x-DIS and its application please consult the documents in Table 23.
Parameter values specified in the datasheet overrule possibly conflicting statements given in references cited in
this datasheet.
Document Name
Description
Source
SHT3x Shipping Package
Information on Tape, Reel and shipping bags
(technical drawing and dimensions)
Available upon request
SHTxx Assembly of SMD
Packages
Assembly Guide (Soldering Instructions)
Available for download at the Sensirion
humidity sensors download center:
www.sensirion.com/humidity-download
SHTxx Design Guide
Design guidelines for designing SHTxx
humidity sensors into applications
Available for download at the Sensirion
humidity sensors download center:
www.sensirion.com/humidity-download
SHTxx Handling Instructions
Guidelines for proper handling of SHTxx
humidity sensors
Available for download at the Sensirion
humidity sensors download center:
www.sensirion.com/humidity-download
Sensirion Humidity Sensor
Specification Statement
Definition of sensor specifications.
Available for download at the Sensirion
humidity sensors download center:
www.sensirion.com/humidity-download
Table 23 Documents containing further information relevant for theSHT3x-DIS.
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 19/20
Revision History
Date
Version
Page(s)
Changes
October 2015
1
-
June 2016
2
2-4
6
7
7
11
17
Specifications for SHT35 added
ESD specifications updated
Table 6 “Comments” section updated
Figure 11 updated according to Table 6
Updated information about data memory to: “After the read out command
“fetch data” has been issued, the data memory is reset, i.e. no measurement
data is present.
Ordering information in Table 22 updated
August 2016
3
6
7
7
8
8
4
Updated Table 3
Updated Table 4
Updated information on ESD testing norm
Updated Table 6
Figure 11 and Table 6 updated
Figure 7 updated
March 2017
4
2-5
9
6
8
15
17
18
19
Updated RH&T accuracy specifications, see Table 1, Table 2, Figure 2,
Figure 5, Figure 8, Figure 9 and Figure 10
Table 7 updated
Table 3 updated
Figure 11 updated
Table 20 updated
Table 21 updated
Figure 15 land pattern drawing simplified (no parameter changed)
Inlcuded: “Parameter values specified in the datasheet overrule possibly
conflicting statements given in references cited in this datasheet.“
Datasheet SHT3x-DIS
www.sensirion.com March 2017 - Version 4 20/20
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 © 2017, by SENSIRION.
CMOSens® is a trademark of Sensirion
All rights reserved.
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