To specify, application notes (ANs) discuss use cases for special and/or new products and the features they offer. While they are technical documents that factor in product operating conditions, which may even offer specific solutions to general usage problems, it is also important to remember that they are marketing materials. Let’s look at both sides of the matter.
The ‘Pro’ Behind App Notes
At first glance, it’s easy to see why many people appreciate and rely on ANs. Aside from detailing technical products and applications, they are available to all sorts of customers, meaning that hobbyists—not just engineers—are made part of a more accessible and communicative industry.
IC manufacturers like Maxim Integrated, for instance, offer over 2,000 ANs (and other technical documents), containing “experienced analysis, design ideas, reference designs, and tutoriala—to make you an expert”, to quote their page.
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Alongside their broad reach to readers, there is also a countless array of benefits that ANs have to offer to general R&D in all manner of industry areas, including the more groundbreaking discussions, such as how to extend wearable battery life, to name just one.
“Customers like app notes. Customers like publications that educate them. ... In application engineering, measurement technique, circuit design technique, whatever, you’ll generate more new customers by printing it all in an app note than you’ll lose [even if] some competitor took your scheme and ran with it.”
So the chief purpose of ANs again reflects why people are fond of them, at least in and of themselves: they aim to educate readers. Williams himself, who was a huge authority on the topic, pushed the importance of manufacturers using them as a way to be forthcoming with product users. As he told Electronics Design Network: “Through application notes that are topic-centred ... an educated customer is a better customer, and an educated customer will come back for more”.
A Word of Warning
It’s the last part of that above quote that answers the question, ‘What’s in it for them?’. It’s important to remember that manufacturers are not just being transparent with readers out of the goodness of their heart. And this is where the said marketing side of ANs comes in; and by extension, authenticity—even accuracy. It’s important to remember that app notes are indeed meant to be informative—but for the chief purpose of sales leads.
ANs are also often uncredited, after all, which means that the writer may not be ‘where the buck stops’. So not all app notes should be taken as gospel—it's even possible that the product’s original design engineer had little to do with them.
Again, consider their marketing nature—unlike customer success stories, which focus on end-user responses (and effectively may have no reason to have inaccuracies), ANs speak for the vendors behind them, so bias information may apply. They may even be written by external copywriters, or potentially anyone who can at least demonstrate a passable industry understanding. This is far from being representative of the primary source.
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One EE hobbyist on industry Q&A forum, Stack Exchange, learned this first hand. Having encountered difficulties in measuring signal frequency with an MCU, their original question on the matter led to some frustrated engineers questioning the accuracy and authenticity of ANs—and ultimately, the hobbyist’s next forum question, simply titled: ‘How reliable are application notes?’
Aside from a more diplomatic EE commenter deeming ANs a ‘mixed bag’, this also led to a response from EE veteran Olin Lathrop, who explained why he thinks you should ignore such documents altogether:
“In many cases, I have seen company structures where most app notes were generated by the customer technical reps, and even Marketing in a few cases. The tech reps write them because they are tired of answering the same question ... over and over again. Marketing writes them because they want to show off how to use the product in a particular application they'd like to sell more into.”
Weighing Up App Notes
Fundamentally then, it is a case of ‘buyer beware’, but not buyer disregard altogether! Lathrop warns of the worst-case scenario: ANs that are unreliable and of questionable origin. But on the other hand, Jim Williams from Linear helped to promote the importance of reliable ANs that accommodate the interests of well-earned customers, and a good flow of communication in the industry.
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Bearing in mind both ends of the spectrum, perhaps the best course for engineers is to read ANs with both a pinch of salt and a weathering eye on the writer’s credentials (if and when they’re freely available), and always read them in tandem with other typical EE documents, which may prove all the more reliable.
After all, app notes may be loved for what they bring to the industry; however, when it comes to those that give them a bad reputation, that’s when they’re read with disdain.