DS18B20

The DS18B20 is a digital thermometer integrated circuit originally produced by Maxim Integrated and now part of Analog Devices. It provides Celsius temperature measurements from -55°C to +125°C with a 12-bit resolution of 0.0625°C per LSB. The device communicates over a single-wire (1-Wire) bus and can be powered from a dedicated supply or in parasite power mode, drawing current from the data line during conversion.

Each DS18B20 has a unique 64-bit ROM code, allowing multiple devices to share a single 1-Wire bus. Temperature data is retrieved from the device’s scratchpad memory, with the primary value stored as a 16-bit temperature register that, when interpreted as a signed value and multiplied by 0.0625, yields the temperature in Celsius. The scratchpad also includes configurable alarm thresholds and a CRC for data integrity. The device supports programmable resolution from 9 to 12 bits; higher resolution increases conversion time.

Communication uses the 1-Wire protocol, with commands such as Read ROM, Match ROM, and Skip ROM, followed by Convert T and Read Scratchpad. A temperature conversion must complete before reading the scratchpad; in parasite power mode a strong pull-up on the data line may be required during conversion.

Packaging and variants include standard three-pin packages (such as TO-92) and waterproof stainless-steel probe variants. The DS18B20 is widely used in hobbyist projects (for example with Arduino or Raspberry Pi) as well as in industrial and HVAC sensing due to its simple digital interface, broad temperature range, and support for multiple devices on a single bus.