www.sensirion.com March 2018 - Version 3 1/18
Datasheet STS3x-DIS
High-Accuracy Digital Temperature Sensor IC
Fully calibrated and linearized digital output
Wide supply voltage range, from 2.15 V to 5.5 V
I2C Interface with communication speeds up to 1
MHz and two user selectable addresses
Typical accuracy of up to 0.1 °C
Very fast start-up and measurement time
Tiny 8-pin DFN package
Product Summary
The STS3x-DIS is Sensirion’s new high accuracy digital
temperature sensor. It relies on the industry proven
CMOSens® technology, providing for increased
intelligence, reliability and improved accuracy
specifications compared to its predecessors. 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
STS3x-DIS into a great variety of applications.
Additionally, the wide supply voltage range of 2.15 V to
5.5 V guarantees compatibility with a wide range of
applications. All in all, the STS3x-DIS incorporates more
than 15 years of Sensirion’s digital sensor know-how.
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 ....................................................... 4
3 Pin Assignment .................................................... 6
4 Operation and Communication ............................. 7
5 Packaging ........................................................... 13
6 Shipping Package .............................................. 15
7 Quality ................................................................ 16
8 Ordering Information........................................... 16
9 Further Information ............................................. 16
Figure 1 Functional block diagram of the STS3x-DIS. The
CMOSens™ technology allows providing for a fully
calibrated I2C signal.
Datasheet STS3x-DIS
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1 Sensor Performance
1.1 Temperature Sensor Performance
Parameter
Condition
Value
STS30 Accuracy tolerance
typ., 0°C to 65°C
0.2
max.
Figure 2
STS31 Accuracy tolerance
typ., 0°C to 90°C
0.2
max.
Figure 3
STS35 Accuracy tolerance
typ., 20°C to 60°C
±0.1
max.
Figure 4
Repeatability1
Low
0.15
Medium
0.08
High
0.04
Resolution
Typ.
0.01
Specified Range
-
-40 to 125
Response time 2
63%
>2
Long Term Drift
max
<0.03
Table 1 Temperature sensor specification.
1
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.
2
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 STS3x-DIS
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STS30
STS31
Figure 2 Temperature accuracy of the STS30 sensor.
Figure 3 Temperature accuracy of the STS31 sensor.
STS35
Figure 4 Temperature accuracy of the STS35 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)
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2 Specifications
2.1 Electrical Specifications
Parameter
Symbol
Condition
Min.
Typ.
Max.
Units
Comments
Supply voltage
VDD
2.15
3.3
5.5
V
Power-up/down level
VPOR
1.8
2.1
2.15
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)
T= 25°C
-
0.2
2.0
A
Current when sensor is
not performing a
measurement during
single shot mode
idle state
(single shot mode)
T= 125°C
-
-
6.0
idle state
(periodic data
acquisition mode)
-
45
-
A
Current when sensor is
not performing a
measurement during
periodic data acquisition
mode
Measuring
-
600
1500
A
Current consumption
while sensor is
measuring
Average
-
1.7
-
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
3.6
-
33
mW
Depending on the
supply voltage
Table 2 Electrical specifications, typical values are valid for T=25°C, min. & max. values for T=-40°C … 125°C.
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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
1.5
ms
Time between VDD reaching
VPOR and sensor entering idle
state
Soft reset time
tSR
After soft reset.
-
0.5
1.5
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
4.5
ms
The three repeatability modes
differ with respect to
measurement duration, noise
level and energy consumption
tMEAS,m
Medium repeatability
4.5
6.5
ms
tMEAS,h
High repeatability
12.5
15.5
ms
Table 3 System timing specification, valid from -40 °C to 125 °C and VDD,min … VDD, max.
2.3 Absolute Minimum and Maximum Ratings
Stress levels beyond those listed in Table 4 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. Ratings
are only tested each at a time.
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)3
4
kV
ESD CDM (charge device model)4
750
V
Table 4 Minimum and maximum ratings; values may only be applied for short time periods.
3
According to ANSI/ESDA/JEDEC JS-001-2014; AEC-Q100-002.
4
According to ANSI/ESD S5.3.1-2009; AEC-Q100-011.
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3 Pin Assignment
The STS3x-DIS comes in a tiny 8-pin DFN package –
see Table 5.
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 5 STS3x-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 STS3x-DIS are shown
in Table 2. 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 5 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
5
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 Mode5 standard. Communication
5
http://www.nxp.com/documents/user_manual/UM10204.pdf
frequencies up to 1 MHz are supported following the
specifications given in Table 18.
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 5). 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 details5). 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 5.
Figure 5 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 5.
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_STSxx Design Guide”.
3.4 ADDR Pin
Through the appropriate wiring of the ADDR pin the I2C
address can be selected (see Table 6 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 STS3x-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)
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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 6 and Figure 5.
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.
STS3x-DIS
I2C Address in Hex.
representation
Condition
I2C address A
0x4A (default)
ADDR (pin 2)
connected to logic
low
I2C address B
0x4B
ADDR (pin 2)
connected to logic
high
Table 6 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 temperature 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
2. 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 STS3x-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
6
.
After sending a command to the sensor a minimal
waiting time of 1ms is needed before another command
can be received by the sensor.
All STS3x-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 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 STS3x-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 2. 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. 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 7.
With the acknowledgement of the measurement
command, the STS3x-DIS starts measuring the
temperature.
4.3 Measurement Commands for Single Shot
Data Acquisition Mode
In this mode one issued measurement command
triggers the acquisition of a 16 bit temperature value.
During transmission that 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 7. They differ with respect to repeatability (low,
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medium and high) and clock stretching (enabled or
disabled).
The repeatability setting influences the measurement
duration and thus the overall energy consumption of the
sensor. This is explained in section 2.2.
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 7 Measurement commands in single shot mode. The
first “SCL free” block indicates a minimal waiting time of 1ms
(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 result 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. 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.
After having received the checksum for the temperature
value a NACK and stop condition should be sent (see
Table 7).
The I2C master can abort the read transfer with a NACK
condition after any data byte if it is not interested in the
CRC.
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 16 bit temperature values.
In periodic mode different measurement commands can
be selected. The corresponding 16 bit commands are
shown in Table 8. 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.
If a measurement command is issued, while the sensor
is busy with a measurement (measurement durations
see Table 3), it is recommended to issue a break
command first (see section 4.7). Upon reception of the
break command the sensor will abort the ongoing
measurement and enter the single shot mode.
SCL free
SCL free
I2C Address
Temperature MSB
16-bit command
I2C write header
I2C read header
I2C Address
I2C Address
I2C read header
measurement
completed
measurement
ongoing
measurement
ongoing
measurement
ongoing
SCL pulled low
Temperature LSB
16-bit temperature value Checksum
S
S
W P
CRC
P
R
R
clock stretching
disabled
clock stretching
enabled
ACK
ACK
ACK
Command LSBCommand MSB
S
NACK
ACK
ACK
ACK NACK
P
ACK
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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 8 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 9. If no
measurement data is present the I2C read header is
responded with a NACK (Bit 9 in Table 9) 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 9 Fetch Data command (clear blocks are controlled
by the microcontroller, grey blocks by the sensor)
4.7 Break command / Stop Periodic Data
Acquisition Mode
The periodic data acquisition mode can be stopped using
the break command shown in Table 10. 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 will abort the ongoing
measurement and enter the single shot mode. This takes
1ms.
Command
Hex Code
Break
0x3093
Table 10 Break command (clear blocks are controlled by
the microcontroller, grey blocks by the sensor).
4.8 Reset
A system reset of the STS3x-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 STS3x-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 STS3x-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 STS3x-
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 11 should be sent.
It is worth noting that the sensor reloads calibration data
prior to every measurement by default.
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
I2C Address
Temperature MSB
16-bit command
I2C write header
I2C read header
I2C Address
Temperature LSB
16-bit temperature value Checksum
S W P
CRC
R
ACK
ACK
ACK
Command LSBCommand MSB
S
ACK
ACK
ACK
P
NACK
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Command
Hex Code
Soft Reset
0x30A2
Table 11 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
specification6. 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 12.
Command
Code
Address byte
0x00
Second byte
0x06
Reset command using the
general call address
0x0006
Table 12 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 5) 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.
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.
4.9 Heater
The STS3x 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 13 Heater command (clear blocks are controlled by
the microcontroller, grey blocks by the sensor)
4.10 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 14 whereas a description of
the content can be found in Table 16.
Command
Hex code
Read Out of status register
0xF32D
Table 14 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, 10, 4) in the status register can be
cleared (set to zero) by sending the command shown in
Table 15.
Command
Hex Code
Clear status register
0x 30 41
Table 15 Command to clear the status register (clear blocks
are controlled by the microcontroller, grey blocks by the
sensor)
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
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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’
12:11
Reserved
‘00’
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 16 Description of the status register.
4.11 Checksum Calculation
The 8-bit CRC checksum transmitted after each data
word is generated by a CRC algorithm. Its properties are
displayed in Table 17. 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 17 I2C CRC properties.
4.12 Conversion of Signal Output
Measurement data is always transferred as 16-bit values
(unsigned integer). These values are already linearized
and compensated for supply voltage effects. Converting
those raw values into a physical scale can be achieved
using the following formulas.
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
ST denotes the raw sensor output for temperature. The
formulas work only correctly when ST is used in decimal
representation.
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4.13 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
0.53
-
-
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
0.26
-
-
µs
Set-up time for STOP
condition
tSU;STO
0.26
-
-
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
-
-
0.4
V
Table 18 Timing specifications for I2C communication, valid for T=-40°C … 125°C and VDD,min … VDD, max. The nomenclature above is
according to the I2C specification (UM10204, Rev. 6, April 4, 2014).
Figure 6 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
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5 Packaging
STS3x-DIS sensors are provided in a dual flat no leads
(DFN) 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 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.
STS3x-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 STS3x-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 consists 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 8
through the labels T1 & T2.
Figure 7 Top view of the STS3x-DIS illustrating the laser
marking.
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5.2 Package Outline
Figure 8 Dimensional drawing of STS3x-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
Center pad marking
T1xT2
-
0.3x45°
-
mm
indicates the position of pin 1
Table 19 Package outline.
5.3 Land Pattern
Figure 9 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
SHTxx_STSxx_Assembly_of_SMD_Packages , which
can be found on the Sensirion webpage.
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Figure 9 Recommended metal land pattern (left) and stencil apertures (right) for the STS3x-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 10 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
Datasheet STS3x-DIS
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7 Quality
Qualification of the STS3x-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 STS3x-DIS can be ordered in tape and reel
packaging with different sizes, see Table 20. The reels
are sealed into antistatic ESD bags. The document
“SHT3x_STS3x shipping package” that shows the
details about the shipping package is available upon
request.
Name
Quantity
Order Number
STS30-DIS-2.5kS
2500
1-101415-01
STS30-DIS-10kS
10000
1-101414-01
STS31-DIS-2.5kS
2500
1-101416-01
STS31-DIS-10kS
10000
1-101417-01
STS35-DIS-B2.5KS
2500
1-101673-01
STS35-DIS-B10KS
10000
1-101672-01
Table 20 STS3x-DIS ordering options.
9 Further Information
For more in-depth information on the STS3x-DIS and its application please consult the following documents:
Document Name
Description
Source
SHT3x_STS3x Shipping Package
Information on Tape, Reel and shipping bags
(technical drawing and dimensions)
Available upon request
SHTxx_STSxx Assembly of SMD
Packages
Assembly Guide (Soldering Instructions)
Available for download at the Sensirion
temperature sensors download center:
www.sensirion.com/temperature-download
SHTxx_STSxx Design Guide
Design guidelines for designing STSxx
temperature sensors into applications
Available for download at the Sensirion
temperature sensors download center:
www.sensirion.com/temperature-download
Table 21 Documents containing further information relevant for the STS3x-DIS.
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Revision History
Date
Version
Page(s)
Changes
November 2016
1
Initial release
November 2017
2
2
2
3
4
5
6
9
12
14
15
16
Updated Table 1
Improved repeatability
Improved accuracy specifications
Updated Table 2
Updated Table 3
Updated Table 5 and description of pin assignment
Updated Section 4.7
Updated Table 18
Updated Table 19
Updated Figure 9
Updated ordering information in Table 20
March 2018
3
4
6
7
9
10
12
7
all
Updated Table 2
Updated Table 5
Introduced "After sending a command to the sensor a minimal waiting time of
1ms is needed before another command can be received by the sensor" in
section 4.
Changed “20µs” to “1ms” in section 4.7
Updated explanation of the heater in section 4.9
Updated Table 18
Section 4.1 removed “The stop condition is optional.”
Typo correction & reformatting, etc.
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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 © 2018, by SENSIRION.
CMOSens® is a trademark of Sensirion
All rights reserved
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