Datasheet SHT3x-ARP
www.sensirion.com May 2015 - Version 0.93 6/13
3 Pin Assignment
The SHT3x-ARP comes in a tiny 8-pin DFN package –
see Table 6.
Analog voltage out; output
No electrical function; recommended to
connect to VSS
No electrical function; recommended to
connect to VSS
Analog voltage out; output
Reset pin active low; Input; if not used it
is recommended to connect to VDD
No electrical function; recommended to
connect to VSS
Table 6 SHT3x-ARP pin assignment (Transparent top view).
Dashed lines are only visible from the bottom. The die pad is
internally connected to VSS.
3.1 Power Pins (VDD, VSS)
The electrical specifications of the SHT3x-ARP 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 Temperature and Humidity Pin
The physical output of temperature and humidity can be
read out at separated pins, as shown in Table 6. Data is
supplied as ratiometric voltage output. The specification
of the Analog voltage signal and its conversion to
physical values is explained in Section 4.
3.3 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. If not used it is
recommended to connect to VDD.
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.
3.4 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”.
4 Operation and Communication
4.1 Start-up of the sensor
As a first step, the sensor needs to be powered up to
VDD (between 2.4 and 5.5 V). After power-up, the
sensor needs at most 17 ms for providing data as voltage
output on the respective output pins. During that time the
temperature and humidity pins have an undefined state.
4.2 Conversion of the Signal Output
The physical values as measured by the sensor are
mapped to a ratiometric voltage output (VX, x=T, RH as
10 to 90% of VDD). Prior to conversion into a voltage
signal, the physical values are linearized and
compensated for temperature and supply voltage effects
by the sensor. Additionally, the voltage output is
calibrated for each sensor. Hence the relationship
between temperature and humidity and the voltage
output is the same for each sensor, within the limits given
by the accuracy.
This allows to describe the relationship between physical
values (RH and T) and the voltage output for
temperature and humidity (VX, x=T, RH) through a
generic linear formula shown in Equation 1 (for RH) and
Equation 2 (for T), its graphical representation can be
found in Figure 8 & Figure 9.
VDD
R(2,3,7)
RH(1)
T(4)
VDD(5)
VSS(8) die
pad
100nF
nRESET(6)
0.1nF
0.1nF