SHT31 Reference Tables, Pins & Specifications

Pin reference

Signal names, electrical functions and connection guidance

DFN-8 + EP

Physical pin numbers9 pins

Scroll within the table to see all columns and rows.

SHT31 pin functions and connections
Signal	Type	Function & connection
SDA	Bidirectional data	I²C data connection. Connection guidance Pull up to the logic rail; connect to the controller SDA. Open-drain; choose the pullup for bus capacitance and frequency.
ADDR	Address selection	Selects the seven-bit bus address. Connection guidance Tie LOW for 0x44 or HIGH for 0x45; do not leave floating. Keep stable throughout the I²C transaction.
ALERT	Alert output	Indicates configured temperature or humidity limits. Connection guidance Connect to a compatible controller input, or leave open if unused.
SCL	Serial clock	I²C clock connection. Connection guidance Connect to controller SCL with an external pullup. Choose a controller that supports clock stretching if that command mode is used.
VDD	Supply	Positive sensor rail. Connection guidance Use 2.15–5.5 V with 100 nF close to VDD/VSS.
nRESET	Active-low reset	Resets the sensor when pulled LOW. Connection guidance May be left open when unused; an optional pullup to VDD must be at least 2 kΩ. Do not hard-wire this input directly to VDD.
R	Reserved contact	No functional signal. Connection guidance Connect to VSS as directed by the datasheet.
VSS	Ground	Supply and interface return. Connection guidance Connect to controller ground.
EP	Exposed center pad	Underside pad, internally connected to VSS. Connection guidance Solder to a ground land for mechanical support. Contact 9 is the footprint identifier for the unnumbered die pad, not a ninth perimeter pin.

Digital SHT31-DIS variant

Manufacturer-referenced values6 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Supply	2.15–5.5 V	3.3 V in the example
Local bypass	100 nF	Place close to VDD and VSS
Idle / conversion current	0.2 µA / 600 µA typical	Single-shot idle at 25°C; conversion 1.5 mA maximum
Specified ranges	−40°C to +125°C; 0–100%RH	Extended range; normal conditions are narrower
Recommended normal operation	5–60°C and 20–80%RH	Long exposure outside this region can change sensor behavior
Bus pullups	4.7 kΩ in the example	An illustrative short 100 kHz bus; calculate for the real load

Do not confuse operating limits with absolute maximum ratings.

SHT31 grade; do not substitute SHT35 limits

Manufacturer-referenced values6 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Humidity tolerance	±2%RH typical	Use the manufacturer curves for range-dependent maxima
Temperature tolerance	±0.2°C typical over 0–90°C	See the temperature error curve outside this range
Humidity repeatability	0.08%RH typical, high setting	A noise metric, distinct from absolute accuracy
Temperature repeatability	0.04°C typical, high setting	A noise metric, distinct from absolute accuracy
Humidity response	8 s typical to 63%	25°C, 1 m/s airflow, without ART
Temperature response	Greater than 2 s	Depends strongly on mounting and heat exchange

A 16-bit result is not a promise of 16-bit measurement accuracy.

Two-byte command values

Manufacturer-referenced values8 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Single shot, high repeatability	0x2400 / 0x2C06	Without / with clock stretching
Single shot, medium repeatability	0x240B / 0x2C0D	Without / with clock stretching
Single shot, low repeatability	0x2416 / 0x2C10	Without / with clock stretching
Periodic, 1 sample/s, high	0x2130	Fetch with 0xE000
Exit periodic mode	0x3093	Break command
Soft reset	0x30A2	Allow the reset recovery time
Read / clear status	0xF32D / 0x3041	Status is a checked 16-bit word
Heater enable / disable	0x306D / 0x3066	Heater raises sensor temperature; not normal ambient measurement

Use explicit error handling for NACKs and communication timeouts.

Temperature first, humidity second

Manufacturer-referenced values7 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Bytes 0–2	Temperature MSB, LSB, CRC	Unsigned raw word ST
Bytes 3–5	Humidity MSB, LSB, CRC	Unsigned raw word SRH
Temperature	T = −45 + 175 × ST / 65535	Result in °C
Relative humidity	RH = 100 × SRH / 65535	Result in %RH
CRC-8	Polynomial 0x31; initial 0xFF	No reflection; final XOR 0; reset for each word
Reference check	CRC(BE EF) = 92 hex	Manufacturer test vector
Illustrative response	66 66 93 80 00 A2 hex	25.00°C and approximately 50.00%RH

Check all six bytes before updating the displayed measurements.

Supply-dependent maximum conversion time

Manufacturer-referenced values7 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
High repeatability	15 ms at 2.4–5.5 V	15.5 ms at 2.15 V to below 2.4 V
Medium repeatability	6 ms at 2.4–5.5 V	6.5 ms at 2.15 V to below 2.4 V
Low repeatability	4 ms at 2.4–5.5 V	4.5 ms at 2.15 V to below 2.4 V
Power-up	1 ms maximum at 2.4–5.5 V	1.5 ms in the lower supply range
Soft reset	1.5 ms maximum	Wait before another command
Supported I²C clock	Up to 1 MHz	Respect the electrical and rise-time limits
Periodic rates	0.5, 1, 2, 4 or 10 samples/s	Do not mistake sample rate for environmental response time

Choose command mode, bus speed and power budget together.

Top-view numbering; underside pad identified separately

Manufacturer-referenced values7 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
ADDR	VSS → 0x44; VDD → 0x45	Never leave floating
R contact 7	Connect to VSS	Not a spare GPIO
ALERT	Leave open if unused	Optional alarm output
nRESET	Leave open if unused	Optional pullup must be at least 2 kΩ
Center pad	Internally connected to VSS	Soldering supports the package mechanically
DFN outline	2.5 × 2.5 × 0.9 mm nominal	Eight 0.5 mm-pitch perimeter contacts
Authored land pattern	0.55 × 0.25 mm signal lands	1.0 × 1.7 mm rectangular center land; review mask and paste

Keep the sensing opening free of coating, flux residue and enclosure obstructions.