Performance Optimization by Adaptive Control of Material Properties in Portable Electronic Devices

Abstract

We evaluate the potential benefits of using tunable material properties within portable electronic devices for increasing the total power generated across different operating scenarios. In these devices, in addition to the die temperature limits, the user-exposed device skin must be kept within ergonomic comfort limits, requiring adaptive control to balance these constraints. Present thermal management strategies rely on control of the allowed amount of heat generation (performance throttling) to maintain the die and skin temperatures within permissible limits as the operating conditions fluctuate. To address this drawback, we investigate the performance benefits offered by integration of material layers into a representative device that could adaptively control their properties, so as to maximize the heat dissipation while preserving the junction and skin temperatures within prescribed bounds. A steady-state model is employed to identify the required thermal conductivity of the tunable material layers that maximize the device performance. The model predicts that tunable materials could offer a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 15$ </tex-math></inline-formula> %–20% increase in the maximum power that can be dissipated, due to modulation of the junction-to-skin thermal resistance, for a representative platform and range of operating conditions. We demonstrate a case study to understand the effect of introduction of the tunable material on the junction temperature at the peak power dissipation, considering the same upper and lower bounds of thermal conductivity for different device form factors. In summary, the work critically identifies the need for target material properties required to achieve this optimal performance with realistic and modest tuning ratios of the effective material conductivity, which can be used to target future materials development and controls strategies for this application.