DS18B20 | GUILCOR SENSORS

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 ?

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.

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.

Resolution and precision

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.

Example of application – Reading equation of a DS18B20

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).

Integration diagram in an electronic system

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".

Multi-point advantage – Unique ID 64 bits

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

Termal block

More than 1,000,000 probes delivered in 2025

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