The DS18B20-PAR 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-PAR does not need an external power supply because it derives power directly from the data line ("parasite power"). The DS18B20-PAR communicates over a 1-Wire® bus, which 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 +100°C and is accurate to ±0.5°C over a range of -10°C to +85°C. Each DS18B20-PAR has a unique 64-bit identification code, which allows multiple DS18B20-PARs to function on the same 1-wire bus; thus, it is simple to use one microprocessor to control many DS18B20-PARs 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.