Intel CORE2DUO/T7300 Mechanical Design Guidelines - Page 64

Output Weighting Matrix, Proportional-Integral-Derivative PID

Page 64 highlights

Intel® Quiet System Technology (Intel® QST) Figure 7-1. Intel® QST Overview Intel® QST Temperature sensing and response Calculations (PID) Fan to sensor Relationship (Output Weighting Matrix) PECI / SST Fan Commands (PID) PWM Temperature Sensors Fans System Response 7.1.1 7.1.2 Output Weighting Matrix Intel QST provides an Output Weighting Matrix that provides a means for a single thermal sensor to affect the speed of multiple fans. An example of how the matrix could be used is if a sensor located next to the memory is sensitive to changes in both the processor heatsink fan and a 2nd fan in the system. By placing a factor in this matrix additional, the Intel QST could command the processor thermal solution fan and this 2nd fan to both accelerate a small amount. At the system level these two small changes can result in a smaller change in acoustics than having a single fan respond to this sensor. Proportional-Integral-Derivative (PID) The use of Proportional-Integral-Derivative (PID) control algorithms allow the magnitude of fan response to be determined based upon the difference between current temperature readings and specific temperature targets. A major advantage of a PID Algorithm is the ability to control the fans to achieve sensor temperatures much closer to the TCONTROL. Figure 7-2 is an illustration of the PID fan control algorithm. As illustrated in the figure, when the actual temperature is below the target temperature, the fan will slow down. The current FSC devices have a fixed temperature versus PWM output relationship and miss this opportunity to achieve additional acoustic benefits. As the actual temperature starts ramping up and approaches the target temperature, the algorithm will instruct the fan to speed up gradually, but will not abruptly increase the fan speed to respond to the condition. It can allow an overshoot over the target temperature for a short period of time while ramping up the fan to bring the actual 64 Thermal and Mechanical Design Guidelines

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Intel® Quiet System Technology (Intel® QST)
64
Thermal and Mechanical Design Guidelines
Figure 7-1. Intel
®
QST Overview
7.1.1
Output Weighting Matrix
Intel QST provides an Output Weighting Matrix that provides a means for a single
thermal sensor to affect the speed of multiple fans. An example of how the matrix
could be used is if a sensor located next to the memory is sensitive to changes in both
the processor heatsink fan and a 2
nd
fan in the system. By placing a factor in this
matrix additional, the Intel QST could command the processor thermal solution fan
and this 2
nd
fan to both accelerate a small amount. At the system level these two
small changes can result in a smaller change in acoustics than having a single fan
respond to this sensor.
7.1.2
Proportional-Integral-Derivative (PID)
The use of Proportional-Integral-Derivative (PID) control algorithms allow the
magnitude of fan response to be determined based upon the difference between
current temperature readings and specific temperature targets. A major advantage of
a PID Algorithm is the ability to control the fans to achieve sensor temperatures much
closer to the T
CONTROL
.
Figure 7-2 is an illustration of the PID fan control algorithm. As illustrated in the
figure, when the actual temperature is below the target temperature, the fan will slow
down. The current FSC devices have a fixed temperature versus PWM output
relationship and miss this opportunity to achieve additional acoustic benefits. As the
actual temperature starts ramping up and approaches the target temperature, the
algorithm will instruct the fan to speed up gradually, but will not abruptly increase the
fan speed to respond to the condition. It can allow an overshoot over the target
temperature for a short period of time while ramping up the fan to bring the actual
Fan to sensor
Relationship
(Output Weighting Matrix)
Temperature sensing
and response
Calculations
(PID)
Fan Commands
(PID)
Fans
Temperature
Sensors
Intel
®
QST
System Response
PWM
PECI / SST