Intel BX80616I3540, Design Manual, Page: 32 / 72

Sensor Based Thermal Specification Design Guidance
32 Thermal/Mechanical Design Guide
5.3.3 Thermal Solution Validation
5.3.3.1 Test for Compliance to the TTV Thermal Profile
This step is the same as previously suggested for prior products. The thermal solution
is mounted on a test fixture with the TTV and tested at the following conditions:
• TTV is powered to the TDP condition
• Thermal solution fan operating at full speed
• T
AMBIENT
at the boundary condition from Section 5.3.1
The following data is collected: TTV power, TTV T
CASE
, and T
AMBIENT
, and used to
calculate
Ψ
CA
, which is defined as:
Ψ
CA
= (TTV T
CASE
– T
AMBIENT
) / Power
This testing is best conducted on a bench to eliminate as many variables as possible
when assessing the thermal solution performance. The boundary condition analysis as
described in
Section 5.3.1 should help in making the bench test simpler to perform.
5.3.3.2 Thermal Solution Characterization for Fan Speed Control
The final step in thermal solution validation is to establish the thermal solution
performance,
Ψ
CA
and acoustics as a function of fan speed. This data is necessary to
allow the fan speed control algorithm developer to program the device. It also is
needed to asses the expected acoustic impact of the processor thermal solution in the
system.
The characterization data should be taken over the operating range of the fan. Using
the RCHF5 as the example the fan is operational from 600 to 3500 RPM. The data was
collected at several points and a curve was fit to the data see
Figure 5-5 . Taking data at
6 evenly distributed fan speeds over the operating range should provide enough data to
establish a 3-variable equation. By using the equation from the curve fitting a complete
set of required fan speeds as a function of
Ψ
CA
be developed. The results from the
reference thermal solution characterization are provided in Table 5-1 .
The fan speed control device may modulate the thermal solution fan speed (RPM) by
one of two methods a pulse width modulation (PWM) signal or varying the voltage to
the fan. As a result the characterization data needs to also correlate the RPM to PWM or
voltage to the thermal solution fan. The fan speed algorithm developer needs to
associate the output command from the fan speed control device with the required
thermal solution performance as stated in
Table 5-1 . Regardless of which control
method is used, the term RPM will be used to indicate required fan speed in the rest of
this document.
Note: When selecting a thermal solution from a thermal vendor, the characterization data
should be requested directly from them as a part of their thermal solution collateral.