www.sensirion.com May 2015 - Version 0.93 1/21
Datasheet SHT3x-DIS
Humidity and Temperature Sensor
Fully calibrated, linearized, and temperature
compensated digital output
Wide supply voltage range, from 2.4 to 5.5 V
I2C Interface with communication speeds up to 1
MHz and two user selectable addresses
Typical accuracy of 2%RH and 0.3°C
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 mm 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 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
Low signal noise
Content
1 Sensor Performance............................................. 2
2 Specifications ....................................................... 5
3 Pin Assignment .................................................... 7
4 Operation and Communication ............................. 9
5 Packaging ........................................................... 16
6 Shipping Package .............................................. 18
7 Quality ................................................................ 19
8 Ordering Information........................................... 19
9 Further Information ............................................. 19
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
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1 Sensor Performance
1.1 Humidity Sensor Performance
Parameter
Conditions
Value
Units
SHT30 Accuracy tolerance1
Typ.
3
%RH
Max.
Figure 2
%RH
SHT31 Accuracy tolerance1
Typ.
2
%RH
Max.
Figure 4
%RH
Repeatability2
Low
0.2
%RH
Medium
0.15
%RH
High
0.07
%RH
Resolution
Typ.
0.01
%RH
Hysteresis
at 25°C
0.8
%RH
Specified range3
extended4
0 to 100
%RH
Response time5
63%
86
s
Long-term drift
Typ.7
<0.25
%RH/yr
Table 1 Humidity sensor specification
Relative Humidity (%RH)
100
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
90
±3
±3
±3
±3
±3
±3
±3
±3
±3
80
±3
±3
±3
±3
±3
±3
±3
±3
±3
70
±3
±3
±3
±3
±3
±3
±3
±3
±3
60
±3
±3
±3
±3
±3
±3
±3
±3
±3
50
±3
±3
±3
±3
±3
±3
±3
±3
±3
40
±3
±3
±3
±3
±3
±3
±3
±3
±3
30
±3
±3
±3
±3
±3
±3
±3
±3
±3
20
±3
±3
±3
±3
±3
±3
±3
±3
±3
10
±3
±3
±3
±3
±3
±3
±3
±3
±3
0
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
±4.5
0
10
20
30
40
50
60
70
80
SHT30
Temperature (°C)
Figure 2 Tolerance of RH at 25°C for SHT30
Figure 3 Typical tolerance of RH over T for SHT30
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.
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 1.3.
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 1.3. Maximum value is < 0.5 %RH/yr. Value may be higher in environments with vaporized
solvents, out-gassing tapes, adhesives, packaging materials, etc. For more details please refer to Handling Instructions.
±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)
Datasheet SHT3x-DIS
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Relative Humidity (%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
SHT31
Temperature (°C)
Figure 4 Tolerance of RH at 25°C for SHT31
Figure 5 Typical tolerance of RH over T for SHT31
±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)
Datasheet SHT3x-DIS
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1.2 Temperature Sensor Performance
Parameter
Condition
Value
Units
Accuracy tolerance1
Typ. 10 to +55
0.3
°C
Repeatability2
Low
0.16
°C
Medium
0.07
°C
High
0.04
°C
Resolution
Typ.
0.015
°C
Specified Range
-
-40 to 125
°C
Response time 8
63%
>2
s
Long Term Drift
max
<0.03
°C/yr
Table 2 Temperature sensor specification
Figure 6 Tolerance of the temperature sensor in °C for SHT30 and SHT31
1.3 Recommended Operating Condition
The sensor shows best performance when operated within recommended normal temperature and humidity range of 5 –
60 °C and 20 – 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 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.
8
Temperature response times strongly depends on the design-in of the sensor in the final application. Minimal response time can be achieved when the thermalized
sensor at T1 is placed on a well conducting surface with temperature T2.
±0.0
±0.5
±1.0
±1.5
±2.0
-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)
Datasheet SHT3x-DIS
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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
2.2
2.28
2.35
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 below the maximum
slew rate
Supply current
IDD
Not measuring
single shot mode
0.2
0.7
A
Current when sensor is
not performing a
measurement
Not measuring
periodic data
acquisition mode
45
70
A
Current when sensor is
not performing a
measurement
Measuring
800
1500
A
Current consumption
while sensor is
measuring,
Average
2
5
A
Current consumption
(operation with one
measurement per
second at lowest
repeatability)
Alert Output driving
strength
IOH
0.8x VDD
1.5x VDD
2.1x VDD
mA
See also section 3.5
Heater power
PHeater
Heater running
5
25
mW
Depending on the
supply voltage
Table 3 Electrical specifications, Specification are valid at 25°C and typical VDD
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
350
ns
See section 3.6
Measurement duration
tMEAS,l
Low repeatability
2.5
4
ms
The three repeatability modes
differ with respect to current
consumption, measurement
duration and noise level
tMEAS,m
Medium repeatability
4.5
6
ms
tMEAS,h
High repeatability
12.5
15
ms
Table 4 System Timing Specification, Specifications are valid from -40 to 125 °C and 2.4 to 5.5 V
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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 cannot be 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)
4
kV
ESD CDM (charge device model)
750
V
Table 5 Absolute minimum and maximum ratings; values are target specs and not
confirmed by measurements yet
Datasheet SHT3x-DIS
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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
VDD or VSS, 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 connect to VDD
7
R
No electrical function; recommended to
connect 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 7 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 Standard9 are
supported.
The SDA pin is used to transfer data to and from the
sensor. For safe communication, the timing
specifications defined in the I2C manual9 must be met.
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 7). 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 details9). 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 7.
Figure 7 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). Aside from hard wiring the ADDR Pin to
VDD or VSS, it is also possible to use it as a selector pin.
This means that 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.
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 7.
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.
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
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SHT3x-DIS
I2C Address in Hex.
representation
Condition
I2C address A
0x44 (default)
ADDR (pin 2)
connected to VSS
I2C address B
0x45
ADDR (pin 2)
connected to VDD
Table 7 I2C device address
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 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 350 ns 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 connect to VDD.
Datasheet SHT3x-DIS
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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
9
.
All SHT3x-DIS commands and data are mapped to a 16-
bit address space. Additionally, data and commands are
protected with a CRC checksum. This increases
communication reliability. The 16 bits commands to the
sensor already include a 3 bit CRC checksum. Data send
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
up to the master to decide if it wants 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 sleep state for
energy saving. This sleep 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.
9
http://www.nxp.com/documents/user_manual/UM10204.pdf
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 the
data pair 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).
The repeatability setting influences the measurement
duration and the current consumption of the sensor. This
is explained in section 2.2.
During measurement the sensor generally does not
respond to any I2C activity, i.e. I2C read and write
headers are not acknowledged (NACK). However, 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.
If a measurement command is issued, while the sensor
is busy with a measurement (Table 4 shows the
measurement duration), it is recommended to issue a
break command first (see section 4.8). The break
command will immediately stop the ongoing
measurement and the sensor will enter the single shot
mode.
Datasheet SHT3x-DIS
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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 receiving the checksum
for the humidity value a NACK and stop condition should
be send (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 first two bytes of data with the
CRC byte (without processing the CRC data) and abort
the read transfer after reading the second two data bytes
with a NACK.
Bus free
Bus free
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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 2.2 of this datasheet.
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.)
4.6 Readout of Measurement Results for
Periodic Mode
Transmission of the measurement data can be initiated
through the command shown in Table 10. If no
measurement data is present the I2C read header is
responded with a NACK instead of an ACK (Bit 9 in Table
10) and the communication stops.
Command
Hex code
Fetch Data
0x E0 00
Table 10 Data fetch command (Clear blocks are controlled
by the microcontroller, grey blocks by the sensor.)
4.7 ART Command
The unique 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.)
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
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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 using the break command.
Upon reception of the break command the sensor enters
the single shot mode.
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 or when brownout conditions are met.
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.
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
specification9. 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.
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.).
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 350 ns to generate a reset of 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.
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 May 2015 - Version 0.93 13/21
4.10 Heater
The heater 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 18.
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.)
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 17.
Command
Hex Code
Clear status register
0x 30 41
Table 17 Command to clear 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
‘00000’
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 18 Description of the status register
Datasheet SHT3x-DIS
www.sensirion.com May 2015 - Version 0.93 14/21
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 only work
correct when SRH and ST are used in decimal
representation.
Datasheet SHT3x-DIS
www.sensirion.com May 2015 - Version 0.93 15/21
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
60
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
-0.5
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), Specification are at 25°C and typical VDD . The numbers above
are values according to the I2C Specification (UM10204, Rev. 5, October 9 13, 2012)
Figure 8 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 May 2015 - Version 0.93 16/21
5 Packaging
SHT3x-DIS sensors are provided in a 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.
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 10
through the labels T1 & T2.
Figure 9 Top View of the SHT3x-DIS illustrating the laser
marking.
SHT3x
XYABCD
Datasheet SHT3x-DIS
www.sensirion.com May 2015 - Version 0.93 17/21
5.2 Package Outline
Figure 10 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
Not shown in the drawing
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
0.3
0.35
0.4
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 11 shows the land pattern. The land pattern is
understood to be the metal layer 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 mask 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.
E
D
S
A
e
b
D2
E2
L
T1 x T2
Datasheet SHT3x-DIS
www.sensirion.com May 2015 - Version 0.93 18/21
Figure 11 Recommended metal land pattern and stencil apertures for the SHT3x-DIS. The dashed lines represent the outer
dimension of the DFN package. The PCB pads and stencil apertures are indicated through the shaded areas.
6 Shipping Package
Figure 12 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.
1.7
0.25
1
0.5
0.5
0.5
0.55
0.3x45°
0.375
0.2
0.75
0.4
0.9
1.6
0.55
0.5 0.5 0.5
0.25
0.55
0.45
0.8
0.375
0.3
land pattern stencil aperture
sensor outline
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 May 2015 - Version 0.93 19/21
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 packaging
tape with sensor orientation is available upon request.
Name
Quantity
Order Number
SHT30-DIS-B500E
500
1-101256-01
SHT30-DIS-B10kS
10000
1-101173-01
SHT31-DIS-B1kS
1000
1-101177-01
SHT31-DIS-B10kS
10000
1-101147-01
Table 22 SHT3x-DIS ordering options.
9 Further Information
For more in-depth information on the SHT3x-DIS and its
application please consult the following documents:
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 Instruction,)
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 (Reconditioning Procedure)
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 May 2015 - Version 0.93 20/21
Revision History
Date
Version
Page(s)
Changes
November 2014
0.9
Initial release
March 2015
0.91
Table 1 and Table 2, added low and medium repeatability
Table 3, added current consumption for periodic data acquisition mode
Table 4, extended the range for the measurement duration
Table 5, removed MM model due to change in AEC Q100 Rev H, amended
absolute maximum ratings
Section 3.4, added comment on address multiplexing
Table 9, changed example command
Table 11, replaced ART command
Section 4.8, modified reset section
Section 4.12, amended Fahrenheit conversion
Table 19, expanded the definition for SDA hold time
April 2015
0.92
Table 1, amended resolution of the humidity sensor
Table 2, amended resolution of the T-Sensor
Table 2, defined Long term drift as max
Table 3, amended Power-up/down level
Table 3, amended maximum current consumption
Table 4, amended typ. value of the power-up time
Table 4, amended max value of the soft reset value
Table 3,added driving strength of the alert out pin
Section 4.8, amended nReset Pin section
May 2015
0.93
Section 4, Added Break Command Section
Table 3, Amended tSR time
Table 18, modified default values
Section 5, added section paragraph on package standard
Section 8, Added ordering information
Datasheet SHT3x-DIS
www.sensirion.com May 2015 - Version 0.93 21/21
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Switzerland
phone: +41 44 306 40 00
fax: +41 44 306 40 30
info@sensirion.com
http://www.sensirion.com
Sensirion Inc., USA
phone: +1 805 409 4900
info_us@sensirion.com
www.sensirion.com
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phone: +81 3 3444 4940
info@sensirion.co.jp
www.sensirion.co.jp
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phone: +82 31 337 7700 3
info@sensirion.co.kr
www.sensirion.co.kr
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phone: +86 755 8252 1501
info@sensirion.com.cn
www.sensirion.com.cn
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phone: +41 44 927 11 66
info@sensirion.com
www.sensirion.com
To find your local representative, please visit
http://www.sensirion.com/contact
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