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