Sealed DS18B20 Temperature Sensor

  • AMP-X145
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Do you need to measure the temperature in an environment unfavorable to electricity? Why not try this sealed temperature sensor?

This sensor will help you measure the temperature of water in an aquarium or in a kettle, the temperature of the soil for your tomato plants, or you could even use it to measure the temperature outside and not worry about rain. You can even use this as a medical thermometer, especially if you need to measure the temperature of your body.

This temperature sensor is based on the popular DS18B20 chip. It allows you to determine the ambient temperature in a range from -55°C to +125°C (-67°F to 257°F) and receive data in the form of a digital signal with 12-bit resolution over 1-wire protocol. This protocol will allow you to connect a large number of such sensors using only 1 digital port on the controller and using only 2 wires for each sensor - signal and ground. To do this so-called "parasitic power" is used, by which the sensor receives energy directly from the signal line. Each sensor has a unique 64-bit code, stitched in production, which can be used by the microcontroller to communicate with a specific sensor on a common bus. The code for each individual sensor can be read by a separate command.

The DS18B20 has a permanent memory where you can save your boundary values for temperature; when you leave these bounds the sensor will go into alarm mode. On a common bus with many sensors, a microcontroller can find out at the time which they have switched into this mode. Because of this feature, it becomes very easy to identify the problem area in a controlled environment.

The resolution is adjustable and can be from 9 to 12 bits. Lower resolution = faster speed.


The DS18B20 sealed sensor can be connected in two ways:

  • Via three wires: power (red), ground (black) and signal (white).
  • Via two wires: ground(black) and signal (white). Due to the nature of this setup the sensor can occasionally give incorrect readings, which can easily be excluded by filtration.

Regardless of the connection method, the signal wire must be connected to the power through a 4.7 kΩ resistor. When only one sensor is connected a 10 kΩ resistor will work.

To connect the sensor to an Arduino or to a breadboard it would be convenient to use a terminal block.

To connect 1-Wire devices to an Arduino there is a ready made library.


  • Range of Measured Temperatures: −55 to +125°C (-67°F to 257°F)
  • Accuracy: ±0.5 °C within −10 to + 85°C (±1°F within 14°F to 185°F)
  • Data Acquisition Time: 750 ms with 12-bit resolution; 94 ms with 9-bit resolution
  • Power Supply: 3–5.5 V
  • Current Draw during Inactivity: 750 nA
  • Current Draw during Usage: 1 mA