Microchip Technology Inc.’s MCP9804 digital temperature sensor converts temperatures between -40°C and +125°C to a digital word with ±0.25°C/±1°C （typical/maximum） accuracy. The MCP9804 comes with user-programmable registers that provide flexibility to temperature sensing applications. The registers allow user-selectable settings such as Shutdown or Low-Power modes and the specification of temperature Alert window limits and critical output limits. When the temperature changes beyond the specified boundary limits， the MCP9804 outputs an Alert signal. The user has the option of setting the Alert output signal polarity as an active-low or activehigh comparator output for thermostat operation， or as a temperature Alert interrupt output for microprocessorbased systems. The Alert output can also be configured as a critical temperature output only. This sensor has an industry standard 100 kHz， 2-wire， SMBus/I2C compatible serial interface， allowing up to eight or sixteen sensors to be controlled with a single serial bus （see Table 3-2 for available Address codes）。 These features make the MCP9804 ideal for sophisticated， multi-zone， temperature-monitoring applications.