Intel 640 User Guide - Page 89

Board Level PWM and Fan Speed Control Requirements

R

Thermal/Mechanical Design Guide

89

Table 8. ATX FSC Settings

Parameter

Classification

Processor

Thermal Diode

PWM Output

Notes

T

HIGH

Required

T

CONTROL

3

T

LOW

Required

T

CONTROL

– 10 °C

3

Minimum PWM Duty

Cycle

Required

20%

PWM Frequency

Required

21–28 kHz

1

Spin-up time

Suggested

250 – ~500 ms

2

T

AVERAGING

Suggested

35 sec

When T

DIODE

< T

LOW

Suggested

Minimum PWM%

All Fans ON

Suggested

T

CONTROL

+ 3 °C

Hysteresis

Suggested

2 °C

NOTES:

1.

A PWM output set to 25 kHz is the design target for the reference and for the Boxed Intel Processor and

the reference design.

2.

Use the lowest time available in this range for the device selected.

3.

To ensure compliance with the thermal specification, thermal profile and usage of the T

DIODE

for fan

speed control these setting should not be user configurable.

Table 9. Balanced Technology Extended

(

BTX) FSC Settings

Parameter

Classificatio

n

Processor

Thermal Diode

System

Ambient Diode

PWM Output

Notes

T

HIGH

Required

T

CONTROL

54 °C

3,5

T

LOW

Required

T

CONTROL

– 7 °C

47 °C

3,5

Minimum PWM Duty

Cycle

Required

PWM 1 (TMA) -

20%

PWM Frequency

Required

21–28 kHz

1

Spin Up Time

Suggested

250 – ~ 500 ms

2

T

AVERAGING

Suggested

4.0 sec

4.0 sec

3

When T

DIODE

< T

LOW

Suggested

Minimum PWM%

Minimum PWM%

All Fans On

Suggested

T

CONTROL

+ 3 °C

65 °C

Hysteresis

Suggested

2 °C

4 °C

NOTES:

1.

A PWM frequency of 25 kHz is the design target for the reference and for the Intel

®

Boxed Processor

and the reference design.

2.

Use the lowest time available in this range for the device selected

3. T

AVERAGEING

= represents the amount of delay time before responding to the temperature change, defined

in fan speed control device (sometimes called ramp range control or spike smoothing). Please select the

lowest setting available close to 4.0 seconds by the fan speed control device

4.

The Fan Speed Controller, or Health Monitor Component, takes the result of the two fan speed ramps

(processor and system) and drives the TMA fan to the highest resulting PWM duty cycle (%)

5.

For BTX systems, a second thermal sensor is recommended to capture chassis ambient temperature

(for more detail, see Appendix E).

6.

To ensure compliance with the thermal specification, thermal profile and usage of the T

DIODE

for fan

speed control these setting should not be user configurable.

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

Intel 640 User Guide - Page 89

Table 8. ATX FSC Settings, Table 9. Balanced Technology Extended, BTX FSC Settings

Page 89 highlights