Intel Pentium 4 Processor with 512-KB L2 Cache on 0.13 Micron Process Thermal Design Guidelines

Introduction
R
Intel
®
Pentium
®
4 Processor Thermal Design Guide 9
1.3 Definition of Terms
Term Description
T
A
The measured ambient temperature locally surrounding the processor. The ambient
temperature should be measured just upstream of a passive heatsink or at the fan
inlet for an active heatsink.
T
E
The ambient air temperature external to a system chassis. This temperature is
usually measured at the chassis air inlets.
T
C
The case temperature of the processor, measured at the geometric center of the
topside of the IHS.
T
S
The heatsink temperature generally measured at the geometric center of the bottom
surface of a heatsink base.
T
C-MAX
The maximum case temperature as specified in a component specification.
Ψ
CA
Case-to-ambient thermal characterization parameter (Psi). A measure of thermal
solution performance using total package power. Defined as (T
C
– T
A
) / Total
Package Power. Heat source should always be specified for Ψ measurements.
Ψ
CS
Case-to-sink thermal characterization parameter. A measure of thermal interface
material performance using total package power. Defined as (T
C
– T
S
) / Total
Package Power.
Ψ
SA
Sink-to-ambient thermal characterization parameter. A measure of heatsink thermal
performance using total package power. Defined as (T
S
– T
A
) / Total Package Power.
Θ
CA
Case-to-ambient thermal resistance (theta). Defined as (T
C
– T
A
) / Power dissipated
from case to ambient.
Θ
CS
Case-to-sink thermal resistance. Defined as (T
C
– T
S
) / Power dissipated from case to
sink.
Θ
SA
Sink-to-ambient thermal resistance. Defined as (T
S
– T
A
) / Power dissipated from sink
to ambient.
TIM
Thermal Interface Material: The thermally conductive compound between the
heatsink and the processor case. This material fills the air gaps and voids, and
enhances the transfer of the heat from the processor case to the heatsink.
P
MAX
The maximum power dissipated by a semiconductor component.
TDP
Thermal Design Power: a power dissipation target based on worst-case applications.
Thermal solutions should be designed to dissipate the thermal design power.
IHS
Integrated Heat Spreader: a thermally conductive lid integrated into a processor
package to improve heat transfer to a thermal solution through heat spreading.
mPGA478
Socket
The surface mount, Zero Insertion Force (ZIF) socket designed to accept the Intel
®
Pentium
®
4 processor with 512-KB L2 cache on 0.13 micron process.
ACPI
Advanced Configuration and Power Interface.
Bypass
Bypass is the area between a passive heatsink and any object that can act to form a
duct. For this example, it can be expressed as a dimension away from the outside
dimension of the fins to the nearest surface.
Thermal Monitor
A feature on the Pentium 4 processor with 512-KB L2 cache on 0.13 micron process
that can keep the processor’s die temperature within factory specifications under
nearly all conditions.
TCC
Thermal Control Circuit: Thermal Monitor uses the TCC to reduce die temperature by
lowering effective processor frequency when the die temperature is very near its
operating limits.