The DS1821 can function as a standalone thermostat with user-programmable trip-points or as 8-bit temperature sensor with a 1-wire digital interface. The thermostat trip-points are stored in nonvolatile memory, so DS1821 units can be programmed prior to system insertion for true standalone operation. The DS1821 has an operating temperature range of 55C to +125C and is accurate to 1C over a range of 0C to +85C. Communication with the DS1821 is accomplished through the open-drain DQ pin; this pin also serves as the thermostat output. 1-Wire is a registered trademark of Dallas Semiconductor. 1 of 18