This is the latest DS18B20 One Wire Digital Temperature Sensor from Maxim IC (but sourced from Sparkfun). The DS18B20 measures temperature in degrees Celsius with 9 to 12-bit precision, -55C to 125C (+/-0.5C). Each sensor has a unique 64-bit serial number programmed into it which allows for a huge number of sensors to be used on one data bus. The DS18B20 One Wire Digital Temperature Sensor is a wonderful part that is the corner stone of many data-logging and temperature control projects.

Features of the DS18B20 One Wire Digital Temperature Sensor:

Unique 1-Wire® interface requires only one port pin for communication
Each device has a unique 64-bit serial code stored in an onboard ROM
Multidrop capability simplifies distributed temperature sensing applications
Requires no external components
Can be powered from data line. Power supply range is 3.0V to 5.5V
Measures temperatures from –55°C to +125°C (–67°F to +257°F)
±0.5°C accuracy from –10°C to +85°C
Thermometer resolution is user-selectable from 9 to 12 bits
Converts temperature to 12-bit digital word in 750ms (max.)
User-definable nonvolatile (NV) alarm settings
Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition)
Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system