STSC1 Datasheet, PDF (5/13 Pages) List of Unclassifed Manufacturers – High Accuracy Digital Temperature Sensor IC

SCL
1/fSCL
tHIGH
tLOW
tR
tF
70%
30%
tSU;DAT
DATA IN
SDA
tHD;DAT
70%
30%
DATA OUT
SDA
tVD;DAT
tF
tR
70%
30%
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
1
4
2 SCL Serial clock, bidirectional
STSC1
3 SDA Serial data, bidirectional
AXY89
2
3
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.
MCU (master)
SCL IN
SCL OUT
VDD
R_P R_P
SCL
STSC1
(slave)
SDA IN
SDA
SDA OUT
GND
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
I²C address
Bin.
Dec.
Hex.
100’1010
74
0x4A
Table 7 STSC1 I²C device address.
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