Placing the Temp Sensor (TS) on DIMM allows accurate monitoring of the DIMM module temperature to better estimate the DRAM case temperature (Tcase) to prevent it from exceeding the maximum operating temperature of 85 Cel. The chip set throttles the memory traffic based on the actual temperatures instead of the calculated worst-case temperature or the ambient temperature using a temp sensor mounted on the motherboard. There is up to a 30 pct improvement in thin and light notebooks that are using one or two 1G SO-DIMM modules, although other memory modules such as in server applications will also see an increase in system performance. Future uses of the TS will include more dynamic control over thermal throttling, the ability to use the Alarm Window to create multiple temperature zones for dynamic throttling and to save processor time by scaling the memory refresh rate.
The TS consists of an Analog-to-Digital Converter (ADC) that monitors and updates its own temperature readings 8 times per second, converts the reading to a digital data, and latches them into the data temperature registers. User-programmable registers, such as Shutdown or Low-power modes and the specification of temperature event and critical output boundaries, provide flexibility for DIMM temperature-sensing applications.
When the temperature changes beyond the specified boundary limits, the SE98 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 even be configured as a critical temperature output.
The SE98 supports the industry-standard 2-wire I2C-bus/SMBus serial interface. The SMBus TIMEOUT function is supported to prevent system lock-ups. Manufacturer and Device ID registers provide the ability to confirm the identify of the device. Three address pins allow up to eight devices to be controlled on a single bus. To maintain interchangeability with the I2C-bus/SMBus interface the electrical specifications are specified with the operating voltage of 3.0 V to 3.6 V.
