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36 DESIGN007 MAGAZINE I JUNE 2020 new component or with a known component in a new or "new to you" configuration or ap- plication. Having said this, I think everything you read, including datasheets and application notes, should be assumed to be lacking or mis- leading or indeed incorrect/wrong just in case. Shaughnessy: It looks to me as if IC manufac- turers' datasheets are more grounded in facts, while app notes are sometimes overly opti- mistic. Some designers say app notes are used more like marketing materials. Is that a fairly accurate description? Maxfield: It depends on who wrote the appli- cation note and what their purpose was. In some cases, it's true that the marketing team instigates the writing of an application note, in which case they may serve a marketing role. In other cases, the writing of the app note was triggered by the engineering department that created the document in an honest attempt to show how that component may be used. Shaughnessy: I've been wondering why there isn't something like a Yelp for app notes and datasheets. Is it worthwhile to let an IC manu- facturer know that their app notes are inaccu- rate? It seems like they would want to know either way. Maxfield: I think that would be awesome, so long as the people writing the reviews were verified as real users and not paid or company sycophants. But I'm not aware of anything like that out there; on the other hand, I don't de- sign things professionally anymore. Shaughnessy: Have you found any app notes or datasheets that are dead-on accurate? I've heard that app notes for memory devices seem to be a little more accurate because they're more conservatively written. Maxfield: Sure, but only the ones for simple components. In the case of more complex components, how could you tell if it's dead- on accurate? It may look dead-on accurate, but how would you know if it wasn't? On the oth- er hand, I've seen lots of app notes that left something to be desired because they left im- portant information out; the desired informa- tion was included, but not in an easy-to-access way; they presented some of the information in a "fuzzy" way that was subject to misinter- pretation; or they were blatantly and obviously incorrect regarding one or more details. Shaughnessy: What advice would you give to a new EE or PCB designer as far as dealing with app notes and datasheets? Maxfield: First, read Elizabeth Simon's series of articles about how to use datasheets. Sec- ond, after you've made yourself familiar with the document—datasheet or app note—go to an experienced engineer and ask him or her to go through it with you line-by-line so you can learn how they look at it and read it and un- derstand it. Third, follow the maxim "Trust, but verify." Remember that these documents aren't writ- ten by an infallible creator—they are written by people who may have been delegated to the task and have no interest in doing it. The writers may not know the device as well as you might hope, or they may know it, but they might not be very good at explaining things. They may also simply forget to capture some vital piece of information or accidentally write a "3" when they meant to write an "8." Shaughnessy: I appreciate your time, Max. Thanks for your help. Maxfield: Thank you, Andy. DESIGN007 First of all, you can have datasheets and app notes for all sorts of things, including subsystems, systems, products, machines, etc.

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