Design for Life, The pitfalls of reliable power supply design

Focus:

The managing director of a U.K. power supply repair company shares his knowledge of the design factors, component vulnerabilities, and environmental and aging factors that produce power supply failures and advises designers how they can prevent such failures. Much attention is given to capacitors including failure mechanisms for electrolytic capacitors, their impact on output and startup circuits, selection guidelines and alternatives to wet electrolytics; failure mechanisms in film capacitors and selection tips; and failure mechanisms in surface-mount multilayer ceramic capacitors and related design guidelines. With regards to semiconductors, the author also discusses power MOSFET problems related to fast dV/dt on the drain-source voltage and single-event burnout; effects of optocoupler aging (with tips on derating optos for longer life); sources of high transient energies (surges and spikes), benefits of surge immunity, and tips on selecting and implementing surge protection (MOVs, TVSs, and gas discharge tubes) as well as the failure modes for these surge protection devices.

What you’ll learn:

• How to improve power supply reliability through improved power supply design practices
• How to understand common sources of power supply field failures
• How to understand possible failure modes for capacitors, MOSFETs, optocouplers, and surge protection devices in power supply applications

Notes:

Article appears on pages 46-51 of August 2011 issue in article archive. You must register to access articles in this magazine's archive.

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Author & Publication:

Paul Horner, Managing Director of Advance Product Services Ltd., Bodo's Power Systems, Aug 01 2011

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