Intel E2180 Design Guide - Page 109

Legacy Fan Speed Control

Thermal and Mechanical Design Guidelines

109

Appendix E

Legacy Fan Speed

Control

A motherboard design may opt to use a SIO or ASIC based fan speed control device

that uses the existing look up or state based fan speed control.

The fan speed control implementations consist of the following items

•

A motherboard designed with a fan speed controller with the following

functionality:

⎯

PWM fan control output

⎯

Remote Digital thermal sensor measurement capability over the PECI bus for

the processor

⎯

SST bus thermal sensor to measure the on-die thermal diode for all earlier

processors in the 775-land LGA package

•

A motherboard with a 4 pin fan header for the processor heatsink fan.

•

Processor heatsink with 4–wire PWM controlled Fan.

A thermistor in the fan hub is recommended, but not a requirement. The reference

solution and the Boxed Processor will implement a thermistor into the design.

The following sections will discuss the necessary steps to implement Legacy Fan

Speed Control.

Note:

For the rest of this section the term “on-die thermal sensor” will be used

interchangeably for the Digital thermal sensor or on-die thermal diode. On-die thermal

diode will only be used when required for clarity.

E.1

Thermal Solution Design

The first step is to select or design a processor thermal solution that meets the

thermal profile for the processor. See Section

2.2.2 for the definition of the thermal

profile and consult the processor datasheet for the specific values.

The designer needs to ensure that when the heat sink fan is operating at full speed

the thermal solution will meet the T

C-MAX

limits at TDP. The slope of the thermal profile

will allow the designer to make tradeoffs in thermal performance versus the inlet

temperature to the processor fan heatsink.

E.1.1

Determine Thermistor Set Points

A thermistor implemented in the hub of a fan is a first level of fan speed control. It

provides an easy and cost effective means to begin acoustic noise reduction. It will, by

design, run the fan at an appropriate speed based on the ambient conditions.

Chapter

5 and

6 discussed in detail the reference thermal solution, including the

target

Ψ

CA

, and fan speed based on temperature to ensure that T

C-MAX

is not exceeded

for TDP power at a given ambient temperature. The resulting variable speed fan (VSF)

curve is the upper limit on fan speed.

Section	Page
1 Introduction	11
1.1 Document Goals and Scope	11
1.1.1 Importance of Thermal Management	11
1.1.2 Document Goals	11
1.1.3 Document Scope	12
1.2 References	13
1.3 Definition of Terms	13
2 Processor Thermal/Mechanical Information	15
2.1 Mechanical Requirements	15
2.1.1 Processor Package	15
2.1.2 Heatsink Attach	17
2.1.2.1 General Guidelines	17
2.1.2.2 Heatsink Clip Load Requirement	17
2.1.2.3 Additional Guidelines	18
2.2 Thermal Requirements	18
2.2.1 Processor Case Temperature	18
2.2.2 Thermal Profile	19
2.2.3 TCONTROL	20
2.3 Heatsink Design Considerations	21
2.3.1 Heatsink Size	22
2.3.2 Heatsink Mass	22
2.3.3 Package IHS Flatness	23
2.3.4 Thermal Interface Material	23
2.4 System Thermal Solution Considerations	24
2.4.1 Chassis Thermal Design Capabilities	24
2.4.2 Improving Chassis Thermal Performance	24
2.4.3 Summary	25
2.5 System Integration Considerations	25
3 Thermal Metrology	27
3.1 Characterizing Cooling Performance Requirements	27
3.1.1 Example	28
3.2 Processor Thermal Solution Performance Assessment	29
3.3 Local Ambient Temperature Measurement Guidelines	29
3.4 Processor Case Temperature Measurement Guidelines	32
4 Thermal Management Logic and Thermal Monitor Feature	33
4.1 Processor Power Dissipation	33
4.2 Thermal Monitor Implementation	33
4.2.1 PROCHOT# Signal	34
4.2.2 Thermal Control Circuit	34
4.2.2.1 Thermal Monitor	34
4.2.3 Thermal Monitor 2	35
4.2.4 Operation and Configuration	36
4.2.5 On-Demand Mode	37
4.2.6 System Considerations	37
4.2.7 Operating System and Application Software Considerations	38
4.2.8 THERMTRIP# Signal	38
4.2.9 Cooling System Failure Warning	38
4.2.10 Digital Thermal Sensor	38
4.2.11 Platform Environmental Control Interface (PECI)	39
5 Balanced Technology Extended (BTX) Thermal/Mechanical Design Information	41
5.1 Overview of the Balanced Technology Extended (BTX) Reference Design	41
5.1.1 Target Heatsink Performance	41
5.1.2 Acoustics	42
5.1.3 Effective Fan Curve	44
5.1.4 Voltage Regulator Thermal Management	45
5.1.5 Altitude	46
5.1.6 Reference Heatsink Thermal Validation	46
5.2 Environmental Reliability Testing	46
5.2.1 Structural Reliability Testing	46
5.2.1.1 Random Vibration Test Procedure	47
5.2.1.2 Shock Test Procedure	47
5.2.2 Power Cycling	49
5.2.3 Recommended BIOS/CPU/Memory Test Procedures	49
5.3 Material and Recycling Requirements	49
5.4 Safety Requirements	50
5.5 Geometric Envelope for Intel Reference BTX Thermal Module Assembly	50
5.6 Preload and TMA Stiffness	51
5.6.1 Structural Design Strategy	51
5.6.2 TMA Preload versus Stiffness	51
6 ATX Thermal/Mechanical Design Information	55
6.1 ATX Reference Design Requirements	55
6.2 Validation Results for Reference Design	58
6.2.1 Heatsink Performance	58
6.2.2 Acoustics	59
6.2.3 Altitude	60
6.2.4 Heatsink Thermal Validation	60
6.3 Environmental Reliability Testing	61
6.3.1 Structural Reliability Testing	61
6.3.1.1 Random Vibration Test Procedure	61
6.3.1.2 Shock Test Procedure	61
6.3.2 Power Cycling	63
6.3.3 Recommended BIOS/CPU/Memory Test Procedures	63
6.4 Material and Recycling Requirements	63
6.5 Safety Requirements	64
6.6 Geometric Envelope for Intel Reference ATX Thermal Mechanical Design	64
6.7 Reference Attach Mechanism	65
6.7.1 Structural Design Strategy	65
6.7.2 Mechanical Interface to the Reference Attach Mechanism	66
7 Intel® Quiet System Technology (Intel® QST)	69
7.1 Intel® QST Algorithm	69
7.1.1 Output Weighting Matrix	70
7.1.2 Proportional-Integral-Derivative (PID)	70
7.2 Board and System Implementation of Intel® QST	72
7.3 Intel® QST Configuration and Tuning	74

Intel E2180 Design Guide - Page 109

Appendix E, Legacy Fan Speed, Control

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