With App Notes, Trust But Verify


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For this month’s issue on app notes, I checked in with Clive “Max” Maxfield. The author of Bebop to the Boolean Boogie and countless technical articles and blog posts, he has been involved with all manner of app notes and datasheets during his long career. Max shares his thoughts on data. As he points out, “Remember that these documents are not written by an ‘infallible creator.’”

Andy Shaughnessy: Max, you’ve been involved with electronics design in a variety of different segments: ICs, PCBs, programmables, etc. Give us an overview of how you view the role of app notes vs. datasheets for a PCB designer or EE.

Clive “Max” Maxfield: First of all, you can have datasheets and app notes for all sorts of things, including subsystems, systems, products, machines, etc. From my perspective, I usually think of these in terms of electronic components—either discrete components like resistors, capacitors, diodes, transistors, or more complex components like integrated circuits, from op-amps all the way up to microcontrollers and the like. In this context of datasheets vs. app notes, they serve two different purposes. A datasheet summarizes the characteristics and performance of a component. By comparison, an app note briefly describes how a component is to be configured and used for a specific example application.

Shaughnessy: Have you ever written any datasheets or app notes?

Maxfield: I haven’t written any datasheets, but I have written a couple of application notes.

Shaughnessy: We’ve heard from some PCB designers and EEs who work for companies that demand that they follow app notes, but some well-known design instructors advise designers that IC makers’ app notes should be assumed wrong until proven right. What’s your take on this?

Maxfield: I think app notes can be really useful when you are first starting to work with a new component or with a known component in a new or “new to you” configuration or application. Having said this, I think everything you read, including datasheets and application notes, should be assumed to be lacking or misleading or indeed incorrect/wrong just in case.

Shaughnessy: It looks to me as if IC manufacturers’ datasheets are more grounded in facts, while app notes are sometimes overly optimistic. Some designers say app notes are used more like marketing materials. Is that a fairly accurate description?

To read this entire interview, which appears in the June 2020 issue of Design007 Magazine, click here.

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