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 HDC1080 
 Temperature sensors 

High-accuracy humidity and temperature sensor optimized for low-power and high-reliability applications.

 Measurement range
-40 / 125°C

 Temperature accuracy
+/- 0,2°K

 Humidity accuracy
+/- 2,0 % Rh

 Resolution (Rh and T°)
14 bits

 Power supply voltage
2,7 → 5,5V

Conversion time
6ms / 6,5ms

 Typical current
1,2µA(active)

 Price
Medium

What is a HDC1080 sensor ?Operating principleExample of conversionPrinciple diagram (I2C connection)Application areas

What is a HDC1080 sensor ?

The HDC1080 is a high-precision digital temperature and humidity sensor designed by Texas Instruments to replace analog sensors or older models (HTU21D, SHT21, etc.).

With its ultra-low power consumption, 14-bit resolution, and metrological accuracy, it has become a standard in modern embedded environmental sensors.

Operating principle

The HDC1080 integrates:

  • a calibrated thermal diode for temperature,
  • a capacitive humidity sensor,
  • a 14-bit ΔΣ converter and a factory calibration EEPROM.

The conversion formulas are linear and simple:

T(°C) = (S_T × 165) / 65536 − 40

💡 Each measurement is automatically compensated for temperature and humidity.

Example of conversion

Raw measurement (hex) Temperature (°C) Humidity (%)
0x0000 −40,0 0,0
0x8000 +42,5 50,0
0xFFFF +125,0 100,0

🧮 Resolution: 14 bits → 0.01 °C and 0.006 % RH per LSB.

Principle diagram (I2C connection)

+3.3V
 │
[HDC1080]
 │ SDA ─────────┐
 │ SCL ─────────┤── [I²C Microcontroller]
 │ GND

💡 Fixed address: 0x40 — identical to the HTU21D (therefore not stackable without a multiplexer).

Application areas

🌡️ Environmental IoT Sensors

🏠 Home Automation and Connected Air Conditioners

🧠 Ambient Condition Monitoring

🔋 Low Power Devices (batteries, wireless sensors)

🧪 Portable or Integrated Instrumentation



Should I choose a HDC1080 sensor ?

Strengths points

  • 🎯 High precision calibrated factory
         → ±0.2 K and ±2 % RH — one of the best accuracy/energy ratios on the market.
  • 🔋 Ultra low power consumption→ Only 1.2 µA at 1 measurement/second — ideal for battery-powered IoT.
  • 🧱 Robust and stable design
         → Fully digital sensor, insensitive to analog noise.
  • 🧠 Direct replacement for the HTU21D/SHT21
         → Same packaging, same I²C protocol — simple migration.
HDC1080

Weaknesses points

  • 📡 Fixed address (0x40)
         → It is impossible to connect multiple HDC1080s on the same bus without switching.
  • 🌬️ Sensitive to condensation
         → Provide a hydrophobic filter in a humid environment.
  • 💧 No built-in heating
         → Unlike some Sensirion sensors, there is no automatic drying function.

Useful information

Here is some useful information regarding the HDC1080 sensors.

Adress (hex) Name
 Function
0x00 Temperature Register Temperature lecture
0x01 Humidity Register Humidity lecture
0x02 Configuration Register Mode, resolution, low battery
0xFB Manufacturer ID TI Identifier (0x5449)
0xFE Device ID Sensor identifier (0x1050)
0xFF Serial ID Unique serial number 
// Temperature and Humidity Lecture
i2c_start();
i2c_write(0x40 << 1);
i2c_write(0x00);
delay(10);
i2c_start();
i2c_write((0x40 << 1) | 1);
MSB_T = i2c_read_ack();
LSB_T = i2c_read_ack();
MSB_H = i2c_read_ack();
LSB_H = i2c_read_nack();
i2c_stop();

S_T = (MSB_T << 8) | LSB_T;
S_H = (MSB_H << 8) | LSB_H;
temp = (S_T / 65536.0) * 165.0 - 40.0;
rh = (S_H / 65536.0) * 100.0;

✅ Exemple :

S_T = 32 000 → T = 40,5 °C

S_H = 36 000 → RH = 55,0 %

3.3V ───────────┐
                │
               [HDC1080]
                │ SDA ───────┐
                │ SCL ───────┤── MCU (Arduino, ESP32, STM32…)
                │ GND

💡 Provide pull-up resistors of 10 kΩ on SDA/SCL if not present on the board.

Bit Name
 Description
[13] Battery status 1 = Low battery
[12] Temp first Measurement order (T before RH or vice versa)
[10:9] Mode mesure 00 = RH 14b, T 14b / 01 = RH 11b / 10 = T 11b
[8] Heater 1 = Heating ON (rarely used)
[1] Acquisition mode 0 = Sequential / 1 = Individual

💡 The default configuration is already optimal for most cases.

Temperature (°C) Error (K) HR error (%)
−40 ±0,5 ±3,0
0 ±0,2 ±2,0
50 ±0,2 ±2,0
100 ±0,3 ±2,5
125 ±0,5 ±3,5

💡 Excellent stability over time: typical drift <0.25 % RH/year.

 We integrate any sensor into any probe 

Smooth tube probe

 Smooth tube 

Waterproof probe

 Waterproof

Smooth tube probe

 Bayonet

Slot probe

 Slot

Ambient probe

 Atmosphere

Head connection probe

Termal block

Stick-in probe

Stick-in

Thread probe

Thread

Contact probe

Contact

Jacketed probe

Jacketed

PCBA Design

PCBA design

Winding probe

Winding

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