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Figure 3. Typical application circuit. Please note that the positioning of the pins does not reflect the position

on the real sensor (see Table 8).

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].

3.4 ADDR Pin

Through the appropriate wiring of the ADDR pin the I2C address can be selected (see Table 9 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 SHT33-DIS

onto the same bus. 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

9 and Figure 3. 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.

SHT33-DIS

I2C Address in Hex. representation

Condition

I2C address A

0x44 (default)

ADDR (pin 2) connected to logic low

I2C address B

0x45

ADDR (pin 2) connected to logic high

Table 9. 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 RH/T 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 4. Electrical specifications,

typical values T = 25°C, min. & max. values T = −40 °C

… 125 °C. 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.

V

DD

RR

PP

ADDR(2)

ALERT(3)

die

pad

R(7)

SDA(1)

SCL(4)

VDD(5)

VSS(8)

nRESET(6)