Sensor Based Thermal Specification Design Guidance
•When the DTS value is at or below TCONTROL, the fans can be slowed down - just as with prior processors.
•When DTS is above TCONTROL, FSC algorithms will use knowledge of TAMBIENT and ΨCA vs. RPM to achieve the necessary level of cooling.
DTS 1.1 provides another option to do fan speed control without the Tambient data. Please refer to Section 8.4.1 for more details.This chapter will discuss two
implementations. The first is a FSC system that is not provided the TAMBIENT information and a FSC system that is provided data on the current TAMBIENT. Either method will result in a thermally compliant solution and some acoustic benefit by
operating the processor closer to the thermal profile. But only the TAMBIENT aware FSC system can fully utilize the specification for optimized acoustic performance.
In the development of the FSC algorithm it should be noted that the TAMBIENT is expected to change at a significantly slower rate than the DTS value. The DTS value will
be driven by the workload on the processor and the thermal solution will be required to respond to this much more rapidly than the changes in TAMBIENT.
An additional consideration in establishing the fan speed curves is to account for the thermal interface material performance degradation over time.
70 | Thermal/Mechanical Specifications and Design Guidelines |