Microchip Technology Inc.’s MCP9843/98243 digital temperature sensors convert temperature from -40°C and +125°C to a digital word. These sensors meet JEDEC Specification JC42.4-TSE3000B3 and JC42.4-TSE2002B3 Memory Module Thermal Sensor Component. It provides an accuracy of ±0.2°C/±1°C （typical/maximum） from +75°C to +95°C. In addition， MCP98243 has an internal 256 Byte EEPROM which can be used to store memory module and vendor information. The MCP9843/98243 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 boundaries. When the temperature changes beyond the specified Event boundary limits， the MCP9843/98243 outputs an Alert signal at the Event pin. The user has the option of setting the temperature 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 MCP98243 EEPROM is designed specifically for DRAM DIMMs （Dual In-line Memory Modules） Serial Presence Detect （SPD）。 The lower 128 Bytes （address 0x00 to 0x7F） 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 0x80 to 0xFF） can be used for general purpose data storage. These addresses are not write protected. This sensor has an industry standard 2-wire， I 2C compatible serial interface， allowing up to eight devices to be controlled in a single serial bus.