Datasheet SHT3x-DIS

www.sensirion.com

August 2016 - Version 3

8/20

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

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 recommend to be left floating

7

R

No electrical function; to be connected

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 11 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 frequencycan

be freely chosen between 0 to 1000 kHz. Commands

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 Mode11 standard.

Communication frequencies up to 1 Mhz are supported

following the specifications given in Table 20.

11

http://www.nxp.com/documents/user_manual/UM10204.pd f

Both SCL and SDA lines are open-drain I/Os with diodes

to VDD and VSS. Theyshould be connected to external

pull-up resistors (please refer to Figure 11). A device on

the I2C bus mustonlydrive a line to ground.The external

signal high. For dimensioning resistor sizes please take

bus capacityand communication frequencyinto account

(see for example Section 7.1 of NXPs I2C Manual for

more details11). 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 11.

Figure 11 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 itis 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). The ADDR pin can either be connected to

VDD or VSS, or it can be used 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 onlyconstraintis 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.

1

2

3

4

5

8

7

6

V

DD

RR

PP

die

pad