Therminator 2: A Fast Thermal Simulator for Portable Devices

Abstract

Maintaining safe chip and device skin temperatures in small form-factor mobile devices (such as smartphones and tablets) while continuing to add new functionalities and provide higher performance has emerged as a key challenge. This article presents <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Therminator 2</i> , an early stage, fast, full-device thermal analyzer, which generates accurate transient- and steady-state temperature maps of an entire smartphone starting from the application processor and other key device components, extending to the skin of the device itself. Therminator 2 uses advanced numerical optimization techniques to perform steady-state simulations 1.6 times faster than the prior art technique and is capable of performing transient-state simulations in real time and 1.25 times faster than the prior art method. The thermal analysis is sensitive to detailed device specifications (including its material composition and 3-D layout) as well as different use cases (each case specifying the set of active device components and their activity levels.) Therminator 2 considers all major components within the device, builds a corresponding compact thermal model for each component and the whole device, and produces their transient- and steady-state temperature maps. Temperature results obtained by using Therminator 2 have been validated against a commercial computational fluid dynamics (CFDs)-based tool, i.e., Autodesk Simulation CFD, and thermocouple measurements on a Qualcomm Mobile Developer Platform and Google Nexus 5. A case study on a Samsung Galaxy S4 using Therminator 2 is provided to relate the device performance to the skin temperature and investigate the thermal path design.