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EETE JUNE 2013

Publisher André Rousselot +32 27400053 andre.rousselot@eetimes.be Editor-in-Chief Julien Happich +33 153907865 julien.happich@eetimes.be EDITORS Nick Flaherty +44 7710236368 nick.flaherty@eetimes.be Christoph Hammerschmidt +49 8944450209 chammerschmidt@gmx.net CONTRIBUTING EDITORS Paul Buckley +44 1962866460 paul@activewords.co.uk Jean-Pierre Joosting +44 7800548133 jean-pierre.joosting@eetimes.be Circulation & Finance Luc Desimpel luc.desimpel@eetimes.be Advertising Production & Reprints Lydia Gijsegom lydia.gijsegom@eetimes.be Art Manager Jean-Paul Speliers Acounting Ricardo Pinto Ferreira Regional Advertising Representatives Contact information at: http://www.electronics-eetimes.com/en/ about/sales-contacts.html european business press European Business Press SA 7 Avenue Reine Astrid 1310 La Hulpe Tel: +32 (0)2 740 00 50 Fax: +32 (0)2 740 00 59 www.electronics-eetimes.com VAT Registration: BE 461.357.437 RPM: Brussels Company Number: 0461357437 © 2013 E.B.P. SA ELECTRONIC ENGINEERING TIMES EUROPE is published 11 times in 2013 by European Business Press SA, 7 Avenue Reine Astrid, 1310 La Hulpe, Belgium Tel: +32-2-740 00 50 Fax: +32-2-740 00 59 email: info@eetimes.be. VAT Registration: BE 461.357.437. RPM: Nivelles. Volume 15, Issue 6 EE Times P 304128 It is is free to qualified engineers and managers involved in engineering decisions – see: http://www.electronics-eetimes.com/subscribe Copyright 2013 by European Business Press SA. All rights reserved. P 304128 Designing with circuit protection at the forethought By Bharat Shenoy “Smaler, faster , pretier” – these are the main criteria for today’s electronics. A profitable lead for manufacturers, but also quite challenging for design engineers, that have to fit everything together in a much smaller environment. Put safety on top of these requirements and the story is getting even more complex. Complex for both designers and manufactures and ultimately relevant for the end customers, who expect their products to be not only fully functional, but also safe. Imagine the following scenario: morning, jogging, wet weather… running shoes, hosiery, and nylon shirt. Taken together, for a brief moment, they can generate an electrostatic discharge (ESD) of 30,000V - a potential cardiac arrest for the smartphone or any other handheld device that plays your favourite music. Yet, problems associated with over-voltage and over-current still remain an afterthought for most engineers. Why? Because, with their duties expanding and with design cycles compressing, most engineers relegate circuit protection to the end of the to-do list. “Faster” is the word of the day! These days, engineers have to get the form factor done, get the software done, get the prototype built, and prove out the concept. Only then, if at all, will they have time to think about circuit protection. The unfortunate result of leaving such matters to the last minute is that design functionality suffers. With devices getting smaller and smaller, and so many parts having to fit together, engineers can’t find room anymore for circuit protection devices on their printed circuit boards. The result: they end up re-spinning the boards and losing valuable development time, time that could have been saved, had they thought about circuit protection from the very beginning. To make things worse, many times engineers do think of circuit protection, however they hurry up choosing whatever solution is at hand and the wrong protection device, resulting in functional failures, poor reliability, safety issues, shock, or even fire. Considering circuit protection too late in the project can really have some serious repercussions for any design engineer. One such scenario would be to put yourself in a situation where the space is not available for your ESD device. Or, even worse perhaps, you end up settling for a non-optimal location, where the device won’t function the way it’s supposed to. To avoid these scenarios, the best time to start thinking about such matters is after the very moment you’ve picked out the chip set and begun laying out the circuit board. Fuses are simple, everybody understands them, but over-voltage may not be so obvious, and people might not realize the consequences. Take lighting, for instance: people understand lightning but they may not know it travels across the ground and can create huge glitches in power lines a mile away. And this is just one example for why, knowing and understanding the possible threats is so important. To accurately predict a product’s circuit protection needs, the design engineer must first be able to imagine how it will be used. Once the designer understands the environment, he or she can begin making accommodations. Understanding the target environment of the product and the possible threats that might come up with that location will be crucial in selecting the right circuit protection solution. Standards determine the design of every product, all the way down to the circuit protection. Design engineers have the duty to be aware of all relevant standards before even commencing the project. Just like the components themselves, knowing and understanding the regulations that govern certain products locally or internationally, has to be part of the very first design phase as well. Industry whitepapers, product specs, and case studies are always helpful to as a source of information and education but also as examples of what worked in certain situations, possibly similar to yours. Littelfuse, for example, offers its speed2design site, which is geared toward helping time-challenged designers find circuit protection solutions. Bharat Shenoy is Director of Technical Marketing in the Electronics Business Unit of Littelfuse - www.littelfuse.com www.electronics-eetimes.com Electronic Engineering Times Europe June 2013 51


EETE JUNE 2013
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