Available online at www.sciencedirect.com Journal of Power Sources 178 (2008) 467–475 A sustainable power architecture for mobile computing systems Ali Muhtaroglu a,1 , Alex Yokochi b,∗ , Annette von Jouanne a a School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-5501, USA b School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331-2702, USA Received 19 September 2007; received in revised form 29 October 2007; accepted 4 November 2007 Available online 12 November 2007 Abstract Extension of battery life and dissipation of heat from components with high power density are significant challenges in mobile computing platforms. A power architecture suitable for the integration of low voltage, low power renewables into the bus is described in this paper as an innovative, green approach to help both of these issues. The architecture is both scaleable and flexible in order to accommodate the intermittent nature of the renewable energy sources. A new charge pump based boost scheme with fully asynchronous control is utilized as the enabling building block to meet the stringent power dissipation and efficiency requirements of this application. The resulting power electronics do not contain magnetic components and can be integrated into an LSI chip. © 2007 Elsevier B.V. All rights reserved. Keywords: Asynchronous control; Charge pumps; Mobile computing; Renewable sources; Sustainable power management 1. Introduction Extension of battery life to a full workday while preser- ving high mobility is a fundamental concern for Thin and Light computing platforms [1]. Critical development areas have been identified in the industry such as energy efficient cooling (the need to dissipate over 50 W in a size constrained box) [2], higher density energy sources, fast renewable sources, and enhan- ced power and thermal management features [3]. Much work has been done on silicon power efficiency techniques, power management features, and new costly cooling technologies. An approach that has not been thoroughly investigated is to model each platform as an isolated island where access to the resources of the “mainland” entails high cost. This dictates the effective use of energy sources in the vicinity of the computer. In a sepa- rate paper, the authors have examined fundamental issues related to the integration of thermoelectric (TE), photovoltaic (PV) and piezoelectric power modules for battery life extension in mobile computing platforms [4]. ∗ Corresponding author. Tel.: +1 541 737 9357; fax: +1 541 737 4600. E-mail address: alex.yokochi@orst.edu (A. Yokochi). 1 Present address: Department of Electrical and Electronics Engineering, Middle East Technical University, North Cyprus Campus, Turkey. Power conversion efficiency has been identified as a signifi- cant barrier in the feasibility of the integration of these low power renewables from low, intermittent voltage levels to the system dc bus voltage required to charge a battery. This paper will present the implementation of an innovative charge pump boost converter for integration with low power renewables, resulting in enhancements to mobile power architectures for green note- book designs. At the heart of the proposed power conversion system is an asynchronous charge pump designed to achieve net battery life benefits. 2. Integrated sustainable power management The motivation for integrating renewable sources in a mobile computing platform is a direct consequence of the current design trends in thin and light notebook systems. These can be summa- rized as (i) Longer battery life. New technologies [1] drive energy effi- cient operation and longer lasting batteries. (ii) Performance on demand. The performance is expected to scale up to desktop computing capabilities over time. (iii) Compact design. Systems become thinner, smaller, and lighter in order to enable mobility which makes it chal- lenging to cool high power density components. 0378-7753/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2007.11.007