HTU31D RH/T SENSOR IC

Digital Relative Humidity & Temperature Sensor

REV3 01/2021

Page 6

INTERFACES

Pin Assignment

N° Function

Description

1

SDA

Serial Data Output / Input

2

GND

Ground

3

IC_Add

Address Selection

4

RST

Reset

5

VDD

Supply Voltage

6

SCL

Clock

Table 6 Pin Assignment

I²C Communication Pins (SDA / SCL)

SCL is used to synchronize the communication between microcontroller and HTU31D sensor. Since the interface consists of

fully static logic there is no minimum SCL frequency. The SDA pin is used to transfer data in and out of the device. To send a

command to HTU31D sensor, SDA is valid on the rising edge of SCL and shall remain stable while SCL is high. Following the

falling edge of SCL, SDA value may be changed. To guaranty safe communication SDA shall be valid tQS and tQH before the

rising and after the falling edge of SCL, respectively. To read data from HTU31D sensor, SDA is valid tVD after SCL has gone

low and remains valid until the next SCL falling edge.

An external pull-up resistor (e.g. 10kΩ10) on SCL and SDA is required to pull the signal high only for open collector or open drain

technology microcontrollers. In most case, pull-up resistors are internally included in I/O microcontroller circuits.

Figure 4 I2C Typical Application Circuit

Power Pins (VDD / GND)

Typical circuit includes a 100nF decoupling capacitor between VDD and GND, located as close as possible to the sensor.

IC_Add Pin

The IC_Add pin allows the user to dynamically change sensor I2C address to connect multiple sensors on the same I2C network.

The level applied to the IC_Add pin shall remain constant from the start to the end of the 2C communication (see Communication

and Operation section). If IC_Add pin is not used, it is recommended to connect it to GND (I2C address 0x40) or VDD with a

RST Pin

The RST pin can be used to generate a reset of the sensor. A minimum pulse of 1 μs is required to reliably trigger a sensor

reset. If RST pin is not used, it is recommended to connect it to VDD with a 10kΩ series resistance.

10

Pull-up resistor value is valid if the HTU is alone on I²C bus functioning at 100kHz, otherwise please refer to UM10204, Rev. 6, April 4, 2014