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3 Pin Assignment

The SHT33-DIS comes in a 8-pin DFN package

– see Table 8.

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 recommended to be left

floating; can be connected to VDD with a

series resistor of R ≥ 2 kΩ

7

R

No electrical function; to be connected to VSS

8

VSS

Ground

Table 8. SHT33-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 SHT33-DIS are shown in Table 4. 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 3 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

frequency can be freely chosen between 0 to 1000 kHz. Commands with clock stretching according

to I2C Standard13 are 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 Mode13 standard.

Communication frequencies up to 1 Mhz are supported following the specifications given in Table

23. Both SCL and SDA lines are open-drain I/Os with diodes to VDD and VSS. They should be

connected to external pull-up resistors (please refer to 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).).

A device on the I2C bus must only drive a line to ground. The external pull-up resistors (e.g.

Rp = 10 kΩ) are required to pull the signal high. For dimensioning resistor sizes please take bus

capacity and communication frequency into account (see for example section 7.1 of NXPs I2C

Manual for more details13 [2]). 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 3.

13

http://www.nxp.com/documents/user_manual/UM10204.pdf [2]

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