SHTC3 | GUILCOR SENSORS

SHTC3
Temperature sensors

Ultra-low power temperature and humidity sensor designed for IoT and battery-powered applications.

Maximum precision
+/- 0,3°K

Measurement range
-40 / 125°C

Resolution
16 bits

Power supply voltage
1,62 → 3,6V

Sampling rate

1 to 10Hz

I2C adress
0 x 70

Typical current
100µA(active)

Price
Low

What is a TMP102 sensor ?

The SHTC3 is a digital humidity and temperature sensor from Sensirion, a direct successor to the SHTC1, and a more energy-efficient alternative to the SHT31.

It maintains excellent accuracy while reducing power consumption by a factor of 10.

Its compact design and wide voltage range (1.62 V to 3.6 V) make it an ideal choice for battery-operated applications, smartwatches, environmental IoT, or miniaturized embedded sensors.

Operating principle

The SHTC3 integrates:

a capacitive sensor for humidity,
a measurement diode for temperature,
both converted by a 16-bit ADC and digitally compensated before being sent via I²C.

Official Sensirion formulas:

T(°C) = −45 + 175 × (S_T / 65535)

💡 The measurements are factory calibrated — no external compensation needed.

Temperature / humidity curve (Conversion examples)

Raw measurement (hex)	Temperature (°C)	Humidity (%)
0x0000	-45	0,0
0x8000	42,5	50,0
0xFFFF	130	100,0

🧮 Resolution: 16 bits on each channel (T and RH).

Principle diagram (I2C connection)

+3.3V
 │
[SHTC3]
 │ SDA ─────────┐
 │ SCL ─────────┤── [I²C Microcontroller]
 │ GND

💡 Fixed address: 0x70 — therefore, there can only be one SHTC3 per I²C bus.

Application areas

⌚ Wearables and connected objects

🧠 Environmental IoT sensors

🔋 Battery-powered devices (smart tags, watches, portable stations)

🏠 Home automation and ambient control

⚙️ Compact embedded applications

Should I choose a SHTC3 sensor ?

Strengths points

🔋 Ultra low power consumption
→ Less than 0.5 µA in standby, ideal for IoT or long-lasting battery products.
⚙️ Compact and simple to integrate
→ Miniature DFN package, standard I²C protocol and direct equations.
🎯 Good accuracy despite its compactness
→ ±0.3 K and ±2 % RH: more than sufficient for most embedded applications.
🧠 Integrated automatic compensation
→ No external calibration or correction required.

Weaknesses points

🌡️ More robust than the SHT31
→ No integrated PTFE coating, more susceptible to condensation and contaminants.
📡 Fixed I²C address (0x70)
→ It is impossible to connect multiple devices on the same bus without multiplexing.
💧 No independent temperature sensor
→ The two measurements (T and RH) are always linked in the I²C sequence.

Useful information

Here is some useful information regarding the SHTC3 sensors.

Main I²C Commands

Command (hex)	Description
0x3517	Wake up (exit sleep mode)
0xB098	Sleep (sleep mode)
0x7866	High precision measurement, stretched clock
0x58E0	High precision measurement, without stretched clock
0x609C	Low power measurement, without stretched clock
0xE000	State register lecture
0x5D	Soft reset

I²C Reading Example (pseudo-code)

i2c_start();
i2c_write(0x70 << 1);
i2c_write(0x78);
i2c_write(0x66); // High precision mode
delay(15);
i2c_start();
i2c_write((0x70 << 1) | 1);
MSB_T = i2c_read_ack();
LSB_T = i2c_read_ack();
CRC_T = i2c_read_ack();
MSB_RH = i2c_read_ack();
LSB_RH = i2c_read_ack();
CRC_RH = i2c_read_nack();
i2c_stop();

S_T = (MSB_T << 8) | LSB_T;
S_RH = (MSB_RH << 8) | LSB_RH;
temp = -45 + (175.0 * S_T / 65535.0);
rh = 100.0 * S_RH / 65535.0;

✅ Example:

S_T = 31,000 → T = 37.8 °C

S_RH = 41,000 → RH = 62.5 %

Typical integration diagram

1.8V–3.3V ────────┐ │ [SHTC3] │ SDA ─────┐ │ SCL ─────┤── MCU (IoT, STM32, ESP32…) │ GND

💡 Pull-up resistors of 10 kΩ on SDA/SCL are required if not included on the module.

State register bits