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"Reliability and MTBF Overview"Prepared by Scott SpeaksVicor Reliability Engineering
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2 of 10IntroductionReliability is defined as the probability that a device will perform its required functionunder stated conditions for a specific period of time. Predicting with some degree ofconfidence is very dependant on correctly defining a number of parameters. For instance,choosing the distribution that matches the data is of primary importance. If a correctdistribution is not chosen, the results will not be reliable. The confidence, which dependson the sample size, must be adequate to make correct decisions. Individual componentfailure rates must be based on a large enough population and relevant to truly reflectpresent day normal usages. There are empirical considerations, such as determining theslope of the failure rate and calculating the activation energy, as well as environmentalfactors, such as temperature, humidity, and vibration. Lastly, there are electrical stressorssuch as voltage and current.Reliability engineering can be somewhat abstract in that it involves much statistics; yet itis engineering in its most practical form. Will the design perform its intended mission?Product reliability is seen as a testament to the robustness of the design as well as theintegrity of the quality and manufacturing commitments of an organization. This paperexplains the basic concepts of reliability as it applies to power supplies manufactured byVicor.