The Value of Loosely Coupled Libraries in EDA

Continuing my discussion of libraries in EDA tools, what value would a loosely coupled library bring to the table? That is, what value can I get out of a library that doesn’t directly link a symbol to a specific footprint?

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For me, the highest value of loosely coupled libraries comes when the design constraints of what the circuit must do are clear and concise, but the design constraints of the physical board are not yet known. A loosely coupled library allows me to select components in schematic capture without constraining myself to a physical device. A prime example of this is when I know I will be using a particular family of microcontroller, but don’t yet know if I will need to use the QFP or the QFN package variant dependent on the design constraints of the board layout.

Another advantage of a loosely coupled library is that it allows me to design a circuit in schematic capture and use different physical devices for prototyping and production, and in my workflow, allows me to more easily specify alternates to passive components, especially during the “Great MLCC Shortage”.

In comparison to using an atomic library, loosely coupled libraries move the work of selecting orderable part numbers to place in a BOM to the tail end of the design process. For some, this can be advantageous.

Great loosely coupled libraries have been created over time, one of the best I have found and used is included with KiCad, which is free and open source. If you haven’t had the chance to work with it yet, I would highly recommend you should.

Of course, which type of library you use in your favorite EDA Cad tool is completely user preference, and depending on workflow and the type of project, maybe you use both. I do. With that thought in mind, what might the value be in combining such libraries?

About this author

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Reid Landsrud, Senior Applications Engineering Technician, has been with Digi-Key since 2007. He has an Associates of Applied Science in Electronics Technology and Automated Systems from Northland Community and Technical College. Reid is a KiCad fanatic and specializes in PIC microcontrollers. In his spare time, he tinkers with miscellaneous electronics projects and odd mechanical jobs.

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