Design for Portability
A new book explains many of the engineering concepts needed for portable electronics. Portable Electronics: World Class Designs, John Donovan, editor, Newnes Press, Burlington, MA, USA. 2009. $US 49.95. ISBN: 978-1-85617-624-8. (www.newnespress.com)
John Donovan, the chief editor of Portable Design magazine has pulled together 12 chapters from 14 authors to provide engineers with a solid reference and working guide to the design of portable electronic equipment. You cannot learn everything from one 500-page book, but the authors provide slices of design information that includes system-resource partitioning, code optimization, overall low-power techniques, design methods and tools, radio communications and applications, memory systems and storage, and related topics.
When you evaluate, say, a Texas Instruments MSP430 microcontroller or a Luminary Micro ARM MCU, you will have different low-power, code, memory-management, and real-time performance concerns. This book cannot provide that level of detail for each processor family or type of application, but it still delivers useful information about how to think about the design of portable equipment. Of course, books that pull together many authors who each contribute a chapter, necessarily limits the scope of what an author can write about. So, use this book for guidance on overall system issues with some information about specific types of design.
I thought a chapter on analog low-pass filters was out of place in this book, though. Marc T. Thompson, the author of the book "Intuitive Analog Circuit Design," does gives readers a good overview of low-pass-filter design, but if you must design a filter, there's not enough here to sink your teeth into. And the chapter makes no mention of how to design filters for low-power circuits.
My largest concern about this book centers on the dearth of information about sources of power for portable equipment. One chapter, "Systems Level Approach to Energy Conservation" gives readers snapshot views of techniques such as dynamic frequency scaling and dynamic voltage scaling. And the author describes power-saving technologies already implemented in devices from Freescale, Intel, National Semiconductor, Texas Instruments, and others. But topics such as DC-DC converters, battery management and charger circuits, battery tradeoffs and chemistries. or integrating solar power into a system are ignored. Manufacturers of these products offer application notes you can use for design guidance, but the absence of this information from a book about portable design leaves a big hole. Sorry to say I don't know of a good book about power sources for portable equipment, but I welcome your thoughts on useful information sources.
About half the chapters provide a good bibliography so readers can locate more information on a topic. I'll emphasize again that this book provides a "taste" of information about each topic. You will have to rely on other information to put the author's techniques and design methods into practice.
What are your thoughts about, or experiences with, the most difficult aspect of designs of portable electronic devices?
Jon Titus
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