www.sensirion.com Version 2 – September 2015 1/4
Datasheet STSC1
High Accuracy Digital Temperature Sensor IC
Accurate: ±0.3°C typ. accuracy
Small: DFN package, 2 × 2 × 0.7 mm3
Easy-to-use: fully calibrated, linearized I2C output
Low-power: 8.6 µW average power consumption
Fast: Power-up and measurement within 1 ms
Benefits of Sensirion’s CMOSens® Technology
High reliability and long-term stability
Sensor system on a single chip
Designed for mass production
Optimized for lowest cost
Low signal noise
Contents of this Data Sheet
1 Temperature Sensor Specifications .................................. 2
2 Electrical Specifications .................................................... 3
4 Timing Specifications ........................................................ 4
5 Interface Specifications ..................................................... 5
6 Operation and Communication ......................................... 5
7 Quality ............................................................................... 8
8 Packaging and Traceability ............................................... 8
9 Ordering Information ......................................................... 8
10 Technical Drawings ........................................................... 9
11 Further Information.......................................................... 11
Block Diagram
Figure 1 Functional block diagram of the STSC1.
T sensor
Signal conditioning
ADC
I2C interface
Calibration mem.
VDD
VSS
SDA
SCL
Data processing and system control
analog
digital
Product Summary
The STSC1 is a digital temperature sensor designed
especially for applications requiring a highly accurate
temperature measurement. Sensirion’s CMOSens®
technology offers a complete sensor system on a single
chip, consisting of a bandgap temperature sensor, analog
and digital signal processing, A/D converter, calibration
data memory, and a digital communication interface
supporting I2C fast mode.
www.sensirion.com Version 2 – September 2015 2/13
1 Temperature Sensor Specifications
Parameter
Conditions
Value
Units
Accuracy tolerance1
Typ.
0.3
°C
Max.
see Figure 2
°C
Repeatability2
-
0.1
°C
Resolution3
-
0.01
°C
Specified range4
-
–40 to +125
°C
Response time5
63%
<5 to 30
s
Long-term drift6
Typ.
< 0.02
°C/y
Table 1 Temperature sensor specifications.
Figure 2 Typical and maximal accuracy for temperature sensor in °C.
1
For definition of typ. and max. 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 measurement values at constant conditions and is a measure for the noise on the
physical sensor output.
3
Resolution of A/D converter.
4
Specified range refers to the range for which the temperature sensor specification is guaranteed.
5
Temperature response time depends on heat conductivity of sensor substrate and design-in of sensor in application.
6
Max. value is < 0.04°C/y.
±0
±0.5
±1
±1.5
±2
-40 -20 0 20 40 60 80 100 120
ΔT [C]
Temperature [°C]
Maximum accuracy
Typical accuracy
www.sensirion.com Version 2 – September 2015 3/4
2 Electrical Specifications
2.1 Electrical Characteristics
Default conditions of 25 °C and 1.8 V supply voltage apply to values in the table below, unless otherwise stated.
Parameter
Symbol
Conditions
Min
Typ.
Max
Units
Comments
Supply voltage
VDD
-
1.62
1.8
1.98
V
-
Power-up/down level
VPOR
Static power supply
1.05
1.2
1.35
V
-
Supply current
IDD
Idle state
-
0.7
1.5
µA
-
Measurement
-
385
465
µA
Average current consumption
while sensor is measuring7
Average
-
4.8
-
µA
Average current consumption
(continuous operation with one
measurement per second)7
Average power
consumption
-
Average
-
8.6
-
µW
Average power consumption
(continuous operation with one
measurement per second)7
Low level input voltage
VIL
-0.5
-
0.3 VDD
V
-
High level input voltage
VIH
0.7 VDD
-
VDD(max)
+ 0.5
V
-
Low level output voltage
VOL
3 mA sink current
-
-
0.2 VDD
-
-
Table 2 Electrical specifications.
2.2 Absolute Maximum Ratings
Stress levels beyond those listed in Table 3 may cause permanent damage to the device. These are stress ratings only and
functional operation of the device at these conditions cannot be guaranteed. Exposure to the absolute maximum rating conditions
for extended periods may affect the reliability of the device.
Parameter
Rating
Supply voltage, VDD
-0.3 to +2.16 V
Operating temperature range
-40 to +125 °C
Storage temperature range
-40 to +125 °C
ESD HBM
2 kV
ESD MM
200 V
ESD CDM
500 V
Latch up, JESD78 Class II, 125°C
100mA
Table 3 Absolute maximum ratings.
7
These values can be reduced by using the low power measurement mode, see separate application note.
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4 Timing Specifications
4.1 Sensor System Timings
Default conditions of 25 °C and 1.8 V supply voltage apply to values the table below, unless otherwise stated. Max. values are
measured at -30°C and 1.98V supply voltage.
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Comments
Power-up time
tPU
After hard reset, VDD ≥ VPOR
-
182
239
µs
Time between VDD reaching VPU
and sensor entering idle state
Soft reset time
tSR
After soft reset.
-
173
230
µs
Time between ACK of soft reset
command and sensor entering
idle state
Measurement duration
tMEAS
-
-
10.8
14.4
ms
Duration for a temperature
measurement8
Table 4 System timing specifications.
4.2 Communication Timings
Default conditions of 25 °C and 1.8 V supply voltage apply to values in the table below, unless otherwise stated.
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Comments
SCL clock frequency
fSCL
-
0
-
400
kHz
-
Hold time (repeated) START
condition
tHD;STA
After this period, the first
clock pulse is generated
0.6
-
-
µs
-
LOW period of the SCL clock
tLOW
-
1.3
-
-
µs
-
HIGH period of the SCL clock
tHIGH
-
0.6
-
-
µs
-
Set-up time for a repeated
START condition
tSU;STA
-
0.6
-
-
µs
-
SDA hold time
tHD;DAT
-
0
-
-
-
-
SDA set-up time
tSU;DAT
-
100
-
-
ns
-
SCL/SDA rise time
tR
-
20
-
300
ns
-
SCL/SDA fall time
tF
-
20 *
(VDD/5.5)
-
300
ns
-
SDA valid time
tVD;DAT
-
-
-
0.9
µs
-
Set-up time for STOP
condition
tSU;STO
-
0.6
-
-
µs
-
Capacitive load on bus line
CB
-
-
-
400
pF
-
Table 5 Communication timing specifications. The numbers above are values according to the I2C specification.
8
These values can be reduced by using the low power measurement mode, see separate application note.
www.sensirion.com Version 2 – September 2015 5/13
Figure 3 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.
5 Interface Specifications
The STSC1 supports I2C fast mode (SCL clock frequency
from 0 to 400 kHz) with clock stretching. For detailed
information on the I2C protocol, refer to NXP I2C-bus
specification and user manual UM10204, Rev. 4,
February 13, 2012:
http://ics.nxp.com/support/documents/interface/pdf/I2C.bu
s.specification.pdf
The STSC1 comes in a 4-pin package – see Table 6.
Pin
Name
Comments
1
VDD
Supply voltage
2
SCL
Serial clock, bidirectional
3
SDA
Serial data, bidirectional
4
VSS
Ground
Table 6 STSC1 pin assignment (top view). The center pad is
internally connected to VSS.
Power-supply pins supply voltage (VDD) and ground (VSS)
must be decoupled with a 100 nF capacitor that shall be
placed as close to the sensor as possible – see Figure 4.
SCL is used to synchronize the communication between
microcontroller and the sensor. The master must keep the
clock frequency within 0 to 400 kHz as specified in Table 5.
The STSC1 may pull down the SCL line when clock
stretching is enabled.
The SDA pin is used to transfer data in and out of the
sensor. For safe communication, the timing specifications
defined in the I2C manual must be met.
To avoid signal contention, the microcontroller must only
drive SDA and SCL low. External pull-up resistors (e.g.
10 kΩ) are required to pull the signal high. For
dimensioning resistor sizes please take bus capacity
requirements into account. It should be noted that pull-up
resistors may be included in I/O circuits of microcontrollers.
Figure 4 Typical application circuit, including pull-up resistors RP
and decoupling of VDD and VSS by a capacitor.
For good performance of the STSC1 in the application, it is
important to know that the center pad of the STSC1 offers
the best thermal contact to the temperature sensor. For
more information on design-in, please refer to the document
“SHTxx Design Guide”.
For mechanical reasons the center pad should be soldered.
Electrically, the center pad is internally connected to GND
and may be connected to the GND net on the PCB or left
floating.
6 Operation and Communication
All commands and memory locations of the STSC1 are
mapped to a 16-bit address space which can be accessed
via the I2C protocol.
STSC1
Bin.
Dec.
Hex.
I2C address
100’1010
74
0x4A
Table 7 STSC1 I2C device address.
2
1
3
4
STSC1
AXY89
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
SDA
SCL
GND
VDD
MCU (master)
RP
RP
SCL OUT
SDA OUT
SDA IN
SCL IN
C = 100nF
STSC1
(slave)
STSC1
AXY89
www.sensirion.com Version 2 – September 2015 6/13
6.1 Power-Up and Communication Start
Upon VDD reaching the power-up voltage level VPOR, the
STSC1 enters idle state after a duration of tPU. In idle state,
the STSC1 is ready to receive commands from the master
(microcontroller).
Each transmission sequence begins with START condition
(S) and ends with an (optional) 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.
Please note that in case VDD is set to 0 V (GND), e.g. in
case of a power off of the STSC1, the SCL and SDA pads
are also pulled to GND. Consequently, the I2C bus is
blocked while VDD of the STSC1 is set to 0 V.
6.2 Measurement Commands
The STSC1 provides the possibility to define the sensor
behavior during measurement (see Table 8).
Clock Stretching
Enabled
Clock Stretching
Disabled
0x7CA2
0x7866
Table 8 Measurement commands.
6.3 Starting a Measurement
A measurement communication sequence consists of a
START condition followed by the I2C header with the 7-bit
I2C device address and a write bit (write W: ‘0’). The sensor
indicates the proper reception of a byte by pulling the SDA
pin low (ACK bit) after the falling edge of the 8th SCL clock.
Then the sensor is ready to receive a 16-bit measurement
command. Again, the STSC1 acknowledges the proper
reception of each byte with ACK condition. A complete
measurement cycle is presented in Figure 5.
With the acknowledgement of the measurement command,
the STSC1 starts measuring temperature.
6.4 Sensor Behavior during Measurement and
Clock Stretching
In general, the sensor does not respond to any I2C activity
during measurement, i.e. I2C read and write headers are not
acknowledged (NACK). However, when clock stretching
has been enabled by using a corresponding measurement
command, the sensor responds to a read header with an
ACK and subsequently pulls down the SCL line until the
measurement is complete. As soon as the measurement is
complete, the sensor starts sending the measurement
results.
During measurement, the sensor has a current
consumption according to Table 2.
For best possible repeatability of temperature
measurements, it is recommended to avoid any
communication on the I2C bus while the STSC1 is
measuring. For more information, see application note
“SHTC1 Optimization of Repeatibility”.
6.5 Readout of Measurement Results
After a measurement command has been issued and the
sensor has completed the measurement, the master can
read the measurement results 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 temperature data 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 STSC1 does not receive an
ACK from the master after any byte of data, it will not
continue sending data.
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, in order to save time.
6.6 Soft Reset
The STSC1 provides a soft reset mechanism that forces the
system into a well-defined state without removing the power
supply. If the system is in idle state (i.e. if no measurement
is in progress) the soft reset command can be sent to
STSC1 according to Figure 6. This triggers the sensor to
reset all internal state machines and reload calibration data
from the memory.
Command
Hex. Code
Bin. Code
Software reset
0x805D
1000’0000’0101’1101
Table 9 Soft reset command.
6.7 Read-out of ID Register
The STSC1 has an ID register which contains an STSC1-
specific product code. The read-out of the ID register can
be used to verify the presence of the sensor and proper
communication. The command to read the ID register is
shown in Table 10.
Command
Hex. Code
Bin. Code
Read ID register
0xEFC8
1110’1111’1100’1000
Table 10 Read-out command of ID register.
It needs to be sent to the STSC1 after an I2C write header.
After the STSC1 has acknowledged the proper reception of
the command, the master can send an I2C read header and
the STSC1 will submit the 16-bit ID followed by 8 bits of
CRC. The structure of the ID is described in Table 11.
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16-bit ID
xxxx'xxxx’xx 00’0111
bits 5 to 0: STSC1-specific product code
bits 15 to 6: unspecified information
Table 11 Structure of the 16-bit ID. Bits 15:6 of the ID contain
unspecified information (marked as “x”), which may vary from
sensor to sensor, while bits 5:0 contain the STSC1-specific
product code.
6.8 Checksum Calculation
The 8-bit CRC checksum transmitted after each data word
is generated by a CRC algorithm with the properties
displayed in Table 12. The CRC covers the contents of the
two previously transmitted data bytes.
Property
Value
Name
CRC-8
Width
8 bits
Polynomial
0x31 (x8 + x5 + x4 + 1)
Initialization
0xFF
Reflect input
False
Reflect output
False
Final XOR
0x00
Examples
CRC (0x00) = 0xAC
CRC (0xBEEF) = 0x92
Table 12 STSC1 I2C CRC properties.
6.9 Conversion of Signal Output
Measurement data is always transferred as 16-bit values.
These values are already linearized by the STSC1.
Temperature values can be calculated with the formula
given below.
Temperature conversion formula (result in °C):
16
T
2
S
175 45 T
ST denotes the raw sensor output (as decimal value) for
temperature.
6.10 Communication Data Sequences
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
S
ACK
ACK
ACK
P
STSC1 measuring
1
0
0
1
0
1
0
0
0
1
1
1
1
1
0
0
1
0
1
0
0
0
1
0
I2C address + write
Measurement command MSB
Measurement command LSB
Measurement in progress
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
S
NACK
P
STSC1 measuring
STSC1 in idle
state
S
ACK
1
0
0
1
0
1
0
1
1
0
0
1
0
1
0
1
repeated I2C address + read
while meas. is in prog. (polling)
measurement cont’d
measurement
completed
I2C address + read
29
30
31
32
33
34
35
36
37
38
S
ACK
STSC1 measuring,
SCL line pulled low
1
0
0
1
0
1
0
1
I2C address + read
while meas. is in progress
measurement continued
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
ACK
ACK
NACK
P
0
1
1
0
0
1
0
0
1
0
0
0
1
0
1
1
1
1
0
0
0
1
1
1
Temperature MSB
Temperature LSB
Temperature CRC checksum
clock stretching
disabled
clock
stretching enabled
www.sensirion.com Version 2 – September 2015 8/13
Figure 5 Communication sequence for starting a measurement and reading measurement results displaying both clock stretching options.
The numerical example corresponds to a measurement command with clock stretching enabled. The physical values of the transmitted
measurement result is 23.7 °C. Clear blocks are controlled by the microcontroller, grey blocks by the STSC1.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
S
ACK
ACK
ACK
P
1
0
0
1
0
1
0
0
1
0
0
0
0
0
0
0
0
1
0
1
1
1
0
1
I2C address + write
Command MSB
Command LSB
Figure 6 Command access communication sequence. The example shows a soft reset command. Clear blocks are controlled by the
microcontroller, grey blocks by the STSC1.
7 Quality
7.1 Environmental Stability
Qualification of the STSC1 is performed based on the
JEDEC JESD47 qualification test method.
7.2 Material Contents
The device is fully RoHS and WEEE compliant, e.g. free of
Pb, Cd, and Hg.
8 Packaging and Traceability
STSC1 sensors are provided in a DFN package with an
outline of 2 × 2 × 0.7 mm3 and a terminal pitch of 1 mm.
DFN stands for dual flat no leads.
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 a green epoxy-based
mold compound. Please note that the side walls of sensor
are diced and therefore these diced lead frame surfaces are
not covered with the respective plating.
The Moisture Sensitivity Level classification of the STSC1
is MSL1, according to IPC/JEDEC J-STD-020.
All STSC1 sensors are laser marked for easy identification
and traceability. The marking on the sensor consists of two
lines and a pin-1 indicator. The top line contains the sensor
type (STSC1), the bottom line contains a 5-digit,
alphanumeric tracking code. The pin-1 indicator is located
in the top left corner. See Figure 7 for illustration.
Figure 7 Laser marking on STSC1, the top line with the pin-1
indicator and the sensor type, the bottom line with the 5-digit
alphanumeric tracking code.
Reels are also labeled and provide additional traceability
information.
9 Ordering Information
The STSC1 can be ordered in tape and reel packaging with
different sizes. The reels are sealed into antistatic ESD
bags. A drawing of the packaging tape with sensor
orientation is shown in Figure 10.
Quantity
Packaging
Reel Diameter
Order Number
1’000
Tape & Reel
180 mm (7 inch)
1-101118-01
10’000
Tape & Reel
330 mm (13 inch)
1-101085-01
Table 13 STSC1 ordering options.
STSC1
XXXXX
www.sensirion.com Version 2 – September 2015 9/13
10 Technical Drawings
10.1 Package Outline
Figure 8 Package outline drawing of the STSC1. Dimensions are given in millimeters.
0.7
1.6
1
0.7
0.2x45°
0.35
0.35
2
2
www.sensirion.com Version 2 – September 2015 10/13
10.2 Metal Land Pattern
Figure 9 Recommended metal land pattern for STSC1 (all dimensions are in mm). Recommended solder paste stencil thickness is 100µm,
pads on PCB are recommended to be non solder mask defined (NSMD).
10.3 Tape and Reel 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.
www.sensirion.com Version 2 – September 2015 11/13
11 Further Information
For more in-depth information on the STSC1 and its application please consult the following documents:
Document Name
Description
Source
SHTxx/STSxx Assembly of SMD
Packages
Instructions on soldering and processing of
Sensirion SMD devices.
www.sensirion.com
SHTC1 Optimization of
Repeatibility
Measures for optimization of repeatability of
sensor output (also applicable to STSC1).
www.sensirion.com
SHTC1 Low Power Measurement
Mode
Description of SHTC1 low power measurement
mode (also applicable to STSC1).
www.sensirion.com
Table 14 Documents containing further information relevant for the STSC1.
www.sensirion.com Version 2 – September 2015 12/13
Revision History
Date
Version
Page(s)
Changes
23. May 2014
1
all
Initial released version
1. September 2015
2
3
Improved max. idle current
www.sensirion.com Version 2 – September 2015 13/13
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 © 2015, by SENSIRION.
CMOSens® is a trademark of Sensirion
All rights reserved
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