Editing tdp

{{title|Thermal Design Power (TDP)}}
'''Thermal Design Power''' ('''TDP''') is the amount of [[thermal power]] an [[integrated circuit]] generates under T<sub>CASE,MAX</sub>. A TDP of an IC represents that upper point of the thermal profile and is used for determining the appropriate thermal solution design target. TDP is a measure of heat and should not be confused with [[power dissipation]] which is a measure of the rate of [[work]]. 

== Overview ==
As an integrated circuit operates, some of the power applied is dissipated in the form of heat. This heat must consequently be removed from the die and out of the system in order to maintain operational temperature range. The ability to remove heat depends on the power dissipation, ambient temperature, and the thermal resistance of the materials used in the construction of the package.

:[[File:tdp thermal resistance.svg|500px]]


Where the total thermal resistance (ψ<sub>Junction-Ambient</sub>, ψ<sub>JA</sub>) is the thermal resistance of the Junction to Sink (ψ<sub>JS</sub> which also includes ψ<sub>TIM</sub>) and the thermal resistance of the Sink to Ambient (ψ<sub>SA</sub>). Note that this is measured in °C/W. ψ<sub>SA</sub> is a function of the heatsink material, its thermal conductivity, and its geometry.

:<math>\Psi_{\text{JA}} = \Psi_{\text{JS}} + \Psi_{\text{SA}}</math>

Therefore the maximum allowable resistance can be calculated as

:<math>\Psi_{\text{JA}} = \frac{T_\text{Junction} - T_A}{\text{TDP}}</math>

== Thermal Capacitance ==
[[File:sandy bridge dynamic thermal capacitance.png|right|400px]]
If an integrated circuit has been running at relatively cooler temperatures, the various materials such as the heatsink have also cooled. This mean that there is a small amount of time whereby it is possible for the IC to effectively exceed the rated amount of heat generated and have the heatsink quickly absorb this heat while still maintaining the rated TDP. For example, since {{intel|Sandy Bridge (Client)|Sandy Bridge|l=arch}}, Intel has switch to a dynamic thermal capacitance model which allows their chip to take advantage of this short amount of time at run hotter and at {{intel|turbo boost technology|higher frequency}} in order to extract additional performance. To take advantage of this, Intel has a technology called {{intel|Turbo Boost}} which allows the chip to take advantage of this thermal budget.

== Power Virus ==
{{main|power virus}}
It is possible to craft synthetic code that toggles a large number of transistors on and off without doing any real work in order to generate a large amount of heat. This sort of code is almost never indicative of real-world code and could manage to exceed the rated TDP of chip. When this happens the processor's [[thermal control circuitry]] will kick in and throttle the chip in order to restore it to a safe operating range.

== Configurable TDP ==
{{empty section}}

[[Category:power management mechanism]]