The DS1822-PAR digital thermometer provides 9 to 12bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS1822-PAR does not need an external power supply because it derives power directly from the data line ("parasite power"). The DS1822-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 55C to +100C and is accurate to 2.0C over a range of 10C to +85C. Each DS1822-PAR has a unique 64-bit identification code, which allows multiple DS1822-PARs to function on the same 1wire bus; thus, it is simple to use one microprocessor to control many DS1822-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.