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 DS18B20 
 Temperature sensors 

Digital 1‑Wire temperature sensor offering precise, reliable readings from −55 °C to +125 °C for industrial and consumer applications.

 Maximum precision
+/- 0,50°K

 Minimum temperature
-55°C

 Maximum temperature
+125°C

 Minimum dimensions
4 x 6 x 27

 Response time
Fast

 Self-heating
Low

 Price
Low

Drift
Low

What is a DS18B20 sensor ?Operating principleTechnical specificationsWiring configurationSelf-heatingApplication areas

What is a DS18B20 sensor?

The DS18B20 is a digital temperature sensor with a 1-Wire protocol developed by Maxim Integrated (formerly Dallas Semiconductor).

It integrates into a single component:

  • a semiconductor temperature sensor,
  • an analog-to-digital converter (ADC),
  • an internal memory for calibration and unique identification.

Each DS18B20 has a unique 64-bit address, allowing multiple sensors to be chained on a single data line.

It is the preferred sensor for home automation integrators, data loggers, and embedded systems.

Operating principle

The DS18B20 converts the measured temperature into a 16-bit digital signal according to the relationship:

T = Lecture brut / 16

Each least significant bit corresponds to 0.0625 °C (12 bits) or 0.5 °C (9 bits) depending on the chosen resolution.

The 1-Wire bus allows for communication, power (parasitic or 3.0-5.5 V), and addressing via a single data line.

Technical specifications

Parameter Typical value
Measurement range −55 °C → +125 °C
Typical accuracy ±0,5 K (−10 → +85 °C)
Adjustable resolution 9, 10, 11 or 12 bits
Conversion time 93,75 to 750 ms
Nutrition 3.0 → 5.5 V or parasite mode (1-Wire)
Interface Digital (1-Wire bus)
Typical current < 1 mA
Identification code Unique 64 bits per sensor

Protection

TO-92 housing, stainless steel or IP68 sealing (encapsulated versions)

Wiring Configuration

Type Description

Precision

3-wire

VDD + DATA + GND (standard power supply)

✅ Standard

2-wire (parasite)

DATA and combined nutrition

💡 Wiring Economy

Chained (multi-drop)

Multiple DS18B20 on the same 1-Wire line

🏆 Measurement networks

Self-heating

Due to its very low power consumption, the self-heating of the DS18B20 is negligible (< 0.2 °C), even in continuous reading applications.

Application areas

🧠 Measurement and data recording systems (IoT, Arduino, ESP32, Raspberry Pi)

💧 Thermal monitoring of tanks, fluids, and greenhouses

⚙️ Industrial control and HVAC

🧱 Integration into waterproof cables for outdoor applications

🔋 Low-power applications powered by batteries



Should I choose a DS18B20 sensor ?

Strengths points

  • 🧠 Simple digital communication
         → One single cable for data, power, and synchronization: ultra-simplified installation over long distances.
  • 🎯 Stable and calibrated precision
         → The sensor is factory calibrated with an accuracy of ±0.5 K and a drift of < 0.2 K/year — no recalibration required.
  • 🔗 Unique 64-bit addressing
         → Each probe has an individual identifier, allowing dozens to be connected on a single line without interference.
DS18B20 sensors

Weaknesses points

  • 🌡️ Limited to 12 bits resolution
    → So it is 0.0625 °C per step — sufficient for control, but not for laboratory measurements.
  • 💡 Non-instantaneous conversion time
         → Up to 750 ms for a complete measurement, which may be too slow for fast-reacting systems.
  • ⚡ Noise sensitivity on long cables
    → The 1-Wire protocol becomes unstable beyond 15 m without proper shielding or pull-up resistance.

Useful information

Here is some useful information regarding the DS18B20 sensors.

  • The DS18B20 integrates a 12-bit internal analog-to-digital converter (ADC) and a factory calibration EEPROM, ensuring consistent stability and accuracy over time.
Resolution
 No measurement (°C)
 Conversion time
 Typical accuracy (−10 → +85 °C)
 Extended accuracy (−55 → +125 °C)
9 bits 0,5 °C 93,75 ms ±1,0 K ±2,0 K
10 bits 0,25 °C 187,5 ms ±0,75 K ±1,5 K
11 bits 0,125 °C 375 ms ±0,5 K ±1,0 K
12 bits 0,0625 °C 750 ms ±0,5 K ±0,75 K

🔹 Remarks:

The accuracy is independent of the cable or bus length as long as the voltage remains stable.

The typical drift is < 0.2 K/year, with no need for recalibration.

The resolution can be adjusted via the internal configuration register.

The DS18B20 transmits the temperature as a signed 16-bit binary value, with a scaling factor depending on the resolution.

The reading equation is very simple:

T (°C) = Raw value / 16


🔹 Example 1 – Standard reading in 12 bits

The sensor returns the following two bytes:

  • LSB = 0x50
  • MSB = 0x05

Calculation of the raw value:

Raw value 0x0550 = 1360₁₀

T = 1360 / 16 = 85.0 °C

✅ Result: the measured temperature is 85.0 °C.


🔹 Example 2 – Negative Temperature

The sensor returns:

  • LSB = 0x90
  • MSB = 0xFF

Raw value (two's complement):

Raw value 0xFF90 = -112₁₀

T = -112 / 16 = -7.0 °C

✅ Result: the temperature is −7.0 °C.


🔹 Practical notes:

  • The reading is done via the 1-Wire command “Read Scratchpad” (0xBE).
  • The DS18B20 stores 9 bytes of data: temperature, high/low alarm, config, CRC.
  • The resolution is configured via the configuration register (bits R1, R0).

The DS18B20 connects via a 1-Wire bus, using a single line for data and power.

It can be used in normal mode (3 wires) or parasite mode (2 wires).

🔹 Typical components

Component
 Function
DS18B20 1-Wire Digital Temperature Sensor
Pull resistance (4.7 kΩ)
 Maintains the DATA line in a high state
Microcontroller (Arduino, ESP32, STM32, Raspberry Pi)
 1-Wire bus reading
Shielded cable (if >15 m)
 Noise reduction over long distances
Power supply 3.3 V or 5 V
 Voltage source (or parasitic power supply)

🔹 Functional diagram (ASCII)

3-wire mode (classic)

     +3.3V / +5V
         │
        [4.7kΩ]
         │
DATA ────┼──────────────┐
         │              │
        GND            DS18B20
                        │
                       GND

Parasitic mode (2 wires)

DATA ───┬────────────── DS18B20
        │
       GND

(the sensor is powered from the data line via an internal capacitor)

🔹 Operating Principle

1️⃣ The microcontroller sends a 1-Wire reset command, then detects the presence of the sensor.

2️⃣ The DS18B20 responds with its unique 64-bit identifier.

3️⃣ A "Convert T" (0x44) command triggers the temperature conversion.

4️⃣ After the conversion delay (93 to 750 ms), the temperature is read via "Read Scratchpad".

Each DS18B20 is manufactured with a unique 64-bit identifier, composed of:

  • 8 bits: family code (0x28 for DS18B20)
  • 48 bits: unique serial number
  • 8 bits: CRC check

This system allows for:

  • 🔗 Daisy chaining dozens of sensors on a single line (multi-drop).
  • 🧠 Individually identifying each probe, even on the same cable.
  • 🧩 Replacing a sensor without reconfiguring the network (permanent ID).

Example of a unique address:

28-FF-0C-92-87-16-03-7A

✅ Each sensor is automatically recognized, which simplifies maintenance and software configuration.

 We integrate any sensor into any probe 

Smooth tube probe

 Smooth tube 

Waterproof probe

 Waterproof

Bayonet 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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