The MCP98242 digital temperature sensor comes with user-programmable registers that provide flexibility for DIMM temperature-sensing applications. The registers allow user-selectable settings such as Shutdown or Low-Power modes and the specification of temperature event and critical output boundaries. When the temperature changes beyond the specified boundary limits, the MCP98242 outputs an Event signal. The user has the option of setting the Event output signal polarity as either an active-low or active-high comparator output for thermostat operation, or as a temperature event interrupt output for microprocessor-based systems. The Event output can also be configured as a critical temperature output. The EEPROM is designed specifically for DRAM DIMMs (Dual In-line Memory Modules) Serial Presence Detect (SPD). The lower 128 bytes (address 00h to 7Fh) can be Permanent Write Protected (PWP) or Software Reversible Write Protected (SWP). This allows DRAM vendor and product information to be stored and write protected. The upper 128 bytes (address 80h to FFh) can be used for general purpose data storage. These addresses are not write protected. This sensor has an industry standard 2-wire, I2C/ SMBus compatible serial interface, allowing up to eight devices to be controlled in a single serial bus. To maintain interchangeability with the I2C/SMBus interface the electrical specifications are specified with the operating voltage of 3.0V to 3.6V. In addition, a 40 ms (typical) time out is implemented.