Issue link: https://iconnect007.uberflip.com/i/1256432
24 DESIGN007 MAGAZINE I JUNE 2020 Something like 70% of the parts that get used in the electronics industry can be mounted to a circuit board—in which case, having ECAD models for the various ECAD suites is a help- ful thing for people to have. Sometimes, you can't get the part that you want, so you need to get something that's adjacent to it. Having that cross-reference information is useful to peo- ple. We go down through each of these assets. Which are the assets that will help the greatest number of users in the greatest number of cas- es that we can imagine? You'll see on Octopart that most of our parts have datasheets. Barry Matties: We see some of the industry's top design instructors telling their classes, "Don't trust app notes. Assume they're wrong until they're proven right." What do you think about that? Lipman: They might have been being dramat- ic. I'm not sure. And if you're doing aerospace or medical, life-critical information is needed, then you can't simply trust the documentation. Many datasheets will specify how to test the part, so an engineer will set up a test and ver- ify that they see the same thing on the parts that they have on their bench with the data on the datasheet. It's a very rigorous matter to select parts. Somebody that's in an IoT or a hobbyist space probably wouldn't do that. App notes offer a similar type of information. In most cases, the datasheet is like a service- level agreement between the company and the users of their parts. They try very hard to make these datasheets a guarantee of performance and specifically state what they will not guar- antee. At the other end of the spectrum, you'll see many manufacturers that do "demonstra- tion" designs. They'll design a product, such as a smartphone or an IoT application, which would be called a reference design. A reference design might come with board files. It would probably come with a schematic and then a lot of text about testing and the design. It's a demo of how you would build the entire product. In between these reference designs and the datasheet is where app notes would live be- cause they describe not an entire product, but rather a single problem or design challenge. Let's say you have a problem with an unstable startup for a microcontroller design because you have poor power supply sequencing. An app note may say, "Check out our power sup- ply monitor. This will solve your power supply sequencing problems for these complex new designs." App notes are that thing in the mid- dle ground dealing with individual problems as opposed to full designs or individual parts. Matties: Does the industry understand the dis- tinction? It seems like there's some confusion about app notes and datasheets. Lipman: It's remarkable the level of standard- ization that exists in our industry, consider- ing that it's almost completely market based. That being said, there is still a lot of variation from datasheet to datasheet and app note to app note. I've seen datasheets that are Micro- soft Word documents that have probably been typed by interns with almost no component knowledge. I've also seen datasheets that are 1,000 pages long. Those are very different doc- uments, but they share an intent—to accurate- ly describe a single part and its properties. And app notes have technical descriptions and properties but are marketing materials as well. That's another important distinction be- tween app notes and reference designs versus datasheets. The datasheet is sort of a guaran- tee or a representation of things that should be true. But app notes are more like, "Check out what you could do with our part." Different companies will use different quality engineers and have different communication priorities during the building of an app note. There is also a personality-driven aspect to app notes where people will know the writer. It will depend on the person who is writing the app note as to the quality that you get from it. And you have to be aware of this when you read an app note. Especially for things like thermal issues, performance can vary a lot de- pending on design choices. If you plan on de- signing a $3 product and the app note uses an aluminum circuit board to improve cooling, you might want to think twice about paying