Unique 1-wire interface requires only one port pin for communication • Each device has a unique 64-bit serial code stored in an on-board ROM • Multi-drop 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 750 ms (max.) • User-definable nonvolatile alarm settings • Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition) • Software compatible with the DS1822 • Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system PIN ASSIGNMENT PIN DESCRIPTION GND - Ground DQ - Data In/Out VDD - Power Supply Voltage NC - No Connect DESCRIPTION The DS18B20 Digital Thermometer provides 9 to 12–bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20 communicates over a 1-wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of –55°C to +125°C and is accurate to ±0.5°C over the range of –10°C to +85°C. In addition, the DS18B20 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply. Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1–wire bus; thus, it is simple to use one microprocessor to control many DS18B20s distributed over a large area. Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems inside buildings, equipment or machinery, and process monitoring and control systems.