Defining thermal design power based on real-world usage models

The power dissipated by electronic components has been steadily increasing, but financial and form factor restrictions exist on the cooling solution and the pressure is on to improve the power dissipation capability. The main parameter used for designing a component's cooling system is known as Thermal Design Power (TDP). This parameter is used as a steady state power target that the cooling solution must be able to cool. This is not the maximum instantaneous power that can be dissipated by the component, but is the 'average' power that needs to be cooled while running a typical real-world stress application. The difference arises because of the transient nature of real-world applications and the thermal capacitance of the system. The current paper describes a physics based approach to average the instantaneous power dissipated by real-world applications into a meaningful thermal equivalent. An empirical thermal transient model of the component package and cooling solution was built to convert power traces into temperature responses. The predicted temperature responses were then analyzed to come up with a derating factor of up to 25% applied to the maximum instantaneous power. This methodology allows the component TDP to be defined based on real-world usage scenarios, leading to more realistic thermal design targets helping to reduce cost and prevent over-design.