View ds18b20 datasheet:

DS18B20 Programmable Resolution 1-Wire® Digital Thermometer www.dalsemi.com FEATURES PIN ASSIGNMENT • Unique 1-wire interface requires only one DALLAS port pin for communication 8 NC NC 1 18B20 • Each device has a unique 64-bit serial code NC 2 7 NC stored in an on-board ROM 1 2 3 • Multi-drop capability simplifies distributed VDD 3 6 NC temperature sensing applications DQ 4 5 GND • Requires no external components • Can be powered from data line. Power supply 8-pin 150-mil SOIC range is 3.0V to 5.5V (DS18B20Z) • 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 750 ms (max.) 1 2