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Intel 640 User Guide - Page 19

Thermal Profile

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Processor Thermal/Mechanical Information R Figure 2. Processor Case Temperature Measurement Location Measure TC at this point (geometric center of the package) 37.5 mm 2.2.2 37.5 mm Thermal Profile The Thermal Profile defines the maximum case temperature as a function of processor power dissipation. The TDP and Maximum Case Temperature are defined as the maximum values of the thermal profile. By design the thermal solutions must meet the thermal profile for all system operating conditions and processor power levels. The slope of the thermal profile was established assuming a generational improvement in thermal solution performance of about 10% based on previous Intel reference designs. This performance is expressed as the slope on the thermal profile and can be thought of as the thermal resistance of the heatsink attached to the processor, Ψ CA (Refer to Section 3.1). The intercept on the thermal profile assumes a maximum ambient operating condition that is consistent with the available chassis solutions. To determine compliance to the thermal profile, a measurement of the actual processor power dissipation is required. Contact your Intel sales representative for assistance in processor power measurement. The measured power is plotted on the Thermal Profile to determine the maximum case temperature. Using the example in Figure 3 for a processor dissipating 70 W the maximum case temperature is 61 °C. For the Pentium 4 processor in the 775-land LGA package, there are two thermal profiles to consider. The Platform Requirement Bit (PRB) indicates which thermal profile is appropriate for a specific processor. This document will focus on the development of thermal solutions to meet the thermal profile for PRB=1. See the processor datasheet for the thermal profile and additional discussion on the PRB. Thermal/Mechanical Design Guide 19

Section	Page
Contents	3
Figures	6
Tables	7
Revision History	8
1 Introduction	9
1.1 Document Goals and Scope	9
1.1.1 Importance of Thermal Management	9
1.1.2 Document Goals	9
1.1.3 Document Scope	10
1.2 References	11
1.3 Definition of Terms	12
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	22
2.3.4 Thermal Interface Material	23
2.4 System Thermal Solution Considerations	23
2.4.1 Chassis Thermal Design Capabilities	23
2.4.2 Improving Chassis Thermal Performance	23
2.4.3 Summary	24
2.5 System Integration Considerations	24
3 Thermal Metrology	25
3.1 Characterizing Cooling Performance Requirements	25
3.1.1 Example	26
3.2 Processor Thermal Solution Performance Assessment	27
3.3 Local Ambient Temperature Measurement Guidelines	27
3.4 Processor Case Temperature Measurement Guidelines	30
4 Thermal Management Logic and Thermal Monitor Feature	31
4.1 Processor Power Dissipation	31
4.2 Thermal Monitor Implementation	31
4.2.1 PROCHOT# Signal	32
4.2.2 Thermal Control Circuit	32
4.2.3 Operation and Configuration	33
4.2.4 On-Demand Mode	34
4.2.5 System Considerations	34
4.2.6 Operating System and Application Software Considerations	35
4.2.7 On-Die Thermal Diode	35
4.2.7.1 Reading the On-Die Thermal Diode Interface	35
4.2.7.2 Correction Factors for the On-Die Thermal Diode	36
4.2.8 THERMTRIP# Signal	37
4.2.8.1 Cooling System Failure Warning	37
5 Intel® Thermal/Mechanical Reference Design Information	39
5.1 Intel Validation Criteria for the Reference Design	39
5.1.1 Heatsink Performance Target	39
5.1.2 Acoustics	40
5.1.3 Altitude	40
5.1.4 Reference Heatsink Thermal Validation	41
5.1.5 Fan Performance for Active Heatsink Thermal Solution	41
5.2 Environmental Reliability Testing	42
5.2.1 Structural Reliability Testing	42
5.2.1.1 Random Vibration Test Procedure	42
5.2.1.2 Shock Test Procedure	42
5.2.2 Power Cycling	44
5.2.3 Recommended BIOS/Processor/Memory Test Procedures	44
5.3 Material and Recycling Requirements	44
5.4 Safety Requirements	45
5.5 Geometric Envelope for ATX Intel® Reference Thermal Mechanical Design	45
5.6 ATX Reference Thermal Mechanical Solution for the Intel® Pentium® 4 Processor in the 775–Land LGA Package	46
5.7 Reference Attach Mechanism	48
5.7.1 Structural Design Strategy	48
5.7.2 Mechanical Interface to the Reference Attach Mechanism	49
6 Acoustic Fan Speed Control	53
6.1 Acoustic Fan Speed Control	53
6.2 Thermal Solution Design	53
6.2.1 Compliance to Thermal Profile	53
6.2.2 Determine Thermistor Set Points	53
6.2.3 Minimum Fan Speed Set Point	54
6.3 Board and System Implementation	55
6.3.1 Choosing Fan Speed Control Settings	55
6.3.1.1 Temperature to begin Fan Acceleration	56
6.3.1.2 Minimum PWM Duty Cycle	58
6.4 Combining Thermistor and Thermal Diode Control	59

Match case Limit results 1 per page

Processor Thermal/Mechanical Information

Thermal/Mechanical Design Guide

Figure 2. Processor Case Temperature Measurement Location

37.5 mm

Measure T

at this point

(geometric center of the package)

37.5 mm

Measure T

at this point

(geometric center of the package)

37.5 mm

2.2.2

Thermal Profile

The Thermal Profile defines the maximum case temperature as a function of processor power

dissipation. The TDP and Maximum Case Temperature are defined as the maximum values of the

thermal profile. By design the thermal solutions must meet the thermal profile for all system

operating conditions and processor power levels.

The slope of the thermal profile was established assuming a generational improvement in thermal

solution performance of about 10% based on previous Intel reference designs. This performance

is expressed as the slope on the thermal profile and can be thought of as the thermal resistance of

the heatsink attached to the processor,

(Refer to Section 3.1). The intercept on the thermal

profile assumes a maximum ambient operating condition that is consistent with the available

chassis solutions.

To determine compliance to the thermal profile, a measurement of the actual processor power

dissipation is required. Contact your Intel sales representative for assistance in processor power

measurement. The measured power is plotted on the Thermal Profile to determine the maximum

case temperature. Using the example in Figure 3 for a processor dissipating 70 W the maximum

case temperature is 61 °C.

For the Pentium 4 processor in the 775–land LGA package, there are two thermal profiles to

consider. The Platform Requirement Bit (PRB) indicates which thermal profile is appropriate for

a specific processor. This document will focus on the development of thermal solutions to meet

the thermal profile for PRB=1. See the processor datasheet for the thermal profile and additional

discussion on the PRB.