Overview

The SHTC3 is a compact, ultra-low-power digital relative humidity and temperature sensor engineered by Sensirion. Housed in a miniature 2.0×2.0 mm2.0 \times 2.0\text{ mm} 4-pin DFN package, it is designed specifically for battery-driven wearables, smartphones, smart tags, and low-power IoT sensor nodes.

Delivering typical accuracies of ±2.0% RH\pm 2.0\%\ \text{RH} and ±0.2∘C\pm 0.2^\circ\text{C}, the SHTC3 operates across a wide supply voltage range of 1.62V1.62\text{V} to 3.6V3.6\text{V} DC. It features an automated low-power sleep mode drawing only 0.15 μA0.15\ \mu\text{A}, fast wakeup times (240 μs240\ \mu\text{s}), and an I2CI^2C interface (0x70).

Quick reference

Operating voltage (VIN)3.3 V to 5.0 V DC (breakout module with 3.3V LDO regulator)
IC supply voltage (VDD)1.62 V to 3.6 V DC (3.3 V nominal)
InterfaceI2CI^2C Fast-Mode (up to 400 kHz)
Fixed I2CI^2C address0x70
Humidity range & accuracy0% to 100% RH0\%\text{ to }100\%\text{ RH} (±2.0% RH\pm 2.0\%\ \text{RH} typical)
Temperature range & accuracy−40∘C to +125∘C-40^\circ\text{C}\text{ to }+125^\circ\text{C} (±0.2∘C\pm 0.2^\circ\text{C} typical)
Wakeup time240 μs240\ \mu\text{s} from sleep mode to active measurement
Sleep supply current0.15 μA0.15\ \mu\text{A} (150 nA150\text{ nA})

Pinout

Breakout module 4-pin header:

PinNameTypeDescription
1VINPowerSupply power input (+3.3 V to +5.0 V DC)
2GNDPowerGround reference (0 V)
3SCLDigital InputI2CI^2C Serial Clock
4SDADigital Input / OutputI2CI^2C Serial Data

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply Voltage (Module)VVINV_{VIN}3.33.3 / 5.05.5VPower rail with LDO
Active CurrentICCI_{CC}—270430µAActive measurement
Sleep CurrentIsleepI_{sleep}—0.150.6µASleep mode
Temp Accuracy (10∘C…55∘C10^\circ\text{C}\dots 55^\circ\text{C})TaccT_{acc}-0.2±0.2\pm 0.2+0.2°CTypical accuracy
RH Accuracy (20%…80%20\%\dots 80\%)RHaccRH_{acc}-2.0±2.0\pm 2.0+2.0% RHAt 25∘C25^\circ\text{C}
High Precision Measure Timetmeast_{meas}—10.812.1msNormal power mode

I2CI^2C Commands & Calculations

  • Wakeup Command: 0x3517 (Must send before reading measurements).
  • Sleep Command: 0xB098 (Puts chip into 150 nA150\text{ nA} sleep mode).
  • Measure Normal Power (Clock Stretching): 0x7CA2
  • Measure Low Power (Clock Stretching): 0x6458

Temperature Calculation (∘C^\circ\text{C})

Temperature (∘C)=−45.0+175.0×(Raw 16-bit Temp Register65536)\text{Temperature } (^\circ\text{C}) = -45.0 + 175.0 \times \left( \frac{\text{Raw 16-bit Temp Register}}{65536} \right)

Relative Humidity Calculation (% RH\%\text{ RH})

Relative Humidity (% RH)=100.0×(Raw 16-bit RH Register65536)\text{Relative Humidity } (\%\text{ RH}) = 100.0 \times \left( \frac{\text{Raw 16-bit RH Register}}{65536} \right)

Wiring

SHTC3 Pin→Arduino / MCUESP32Notes
VIN5V / 3.3V3.3VPower rail
GNDGNDGNDSystem ground
SCLA5GPIO 22I2CI^2C Clock
SDAA4GPIO 21I2CI^2C Data

Example (SparkFun SHTC3 Arduino Library)

cpp
#include <Wire.h>
#include "SparkFun_SHTC3.h"

SHTC3 mySHTC3;

void setup() {
  Serial.begin(115200);
  Wire.begin();

  Serial.println("SparkFun SHTC3 Sensor Test");

  while (mySHTC3.begin() != SHTC3_Status_Nominal) {
    Serial.println("SHTC3 initialization failed! Retrying...");
    delay(1000);
  }
}

void loop() {
  SHTC3_Status_TypeDef status = mySHTC3.update();

  if (status == SHTC3_Status_Nominal) {
    Serial.print("Temperature: "); Serial.print(mySHTC3.toDegC()); Serial.print(" °C | ");
    Serial.print("Humidity: "); Serial.print(mySHTC3.toPercent()); Serial.println(" % RH");
  }

  delay(2000);
}

Common mistakes

  • Forgetting to send Wakeup command (0x3517): The SHTC3 boots into sleep mode to conserve battery power. Sending measurement commands without issuing a Wakeup command results in NACK responses over I2CI^2C.
  • Expecting address 0x40: Unlike the SHT21, HTU21D, or HDC1080, the SHTC3 uses I2CI^2C address 0x70.

Notes

  • SHTC3 vs SHT40: SHTC3 uses I2CI^2C address 0x70 and requires manual Wake/Sleep commands; SHT40 uses address 0x44 and auto-sleeps.

Assets & downloads