Influence of temperature control limits on passively cooled computing system performance

Passively-cooled electronic systems such as tablet computers and cell phones commonly are thermally limited by the allowable touch temperature of their surfaces. These systems typically cannot cool maximum processor power in steady state and simultaneously meet surface temperature restrictions. The primary surface temperature control method for thin mobile devices is to limit power, typically resulting in lower computing performance. Improved thermal designs allow higher power dissipation and therefore increased computing performance. Thermal and mechanical design engineers typically operate in terms of temperature for a given power, and this is not usually translated to computing performance. It can be difficult to justify a better thermal design if it is not quantified in its utility to the user. This paper quantifies the tradeoffs between thermal solution performance/temperature control limits and computing performance for two tablet computers and one cell phone that all use the same type of SoC processor.