The iButton® temperature logger (DS1920) provides direct-to-digital 9-bit temperature readings over a range of -55°C to +100°C in 0.5° increments. The iButton communicates with a processor using the 1-Wire® protocol through a hardware port interface. The port interface provides both the physical link and handles the communication protocols that enable the processor to access iButton resources with simple commands. Two bytes of EEPROM can be used either to set alarm triggers or for storing user data.

Armored in the DS1920, the thermometer can measure temperatures in demanding environments. Like every other iButton device, the DS1920 has a unique serial number. The 1-Wire interface reduces data output, address, and power to one line. A unique serial number allows multiple 1920s to share the same bus, with many sensors placed at different sites reporting to a single port on a processor. Multidropped DS1920s make the lowest-power temperature sensing network available inside buildings, equipment, or machinery and in process monitoring and control. With appropriate accessories the DS1920 easily attaches to an object or circuit board.