PCB Circuit Design Tips: Standard vs. Specialized Component Selection

September 18, 2017 Altium Designer

Hovercraft

 

 

 

As a kid, I was fascinated by hovercraft. These nearly frictionless vehicles go from land to water without pause and spin 360s on demand like a carnival ride. I knew that the cost of a full-scale build would require mowing every yard in the country, so instead, I started by constructing a homemade radio controlled model. It worked beautifully on ponds and flat parking lots, but in our hilly corner of the woods, the sleek craft required all of the small motor’s power just to inch up a slight incline. For all of its amazing qualities, it was simply the wrong design for where I lived. It taught me that designs should be specifically tailored to their application. In electronics, the components you use in your circuits will influence the success of your design in its intended application. This is why it is important to carefully consider whether your PCB circuit should be designed with specialized or standard components. Here are some of the approaches that I take to determine which components will be best suited to my design’s intended application.

 

What are Standard and Specialized Components?

Once the scope of a project is defined and the functional block diagram has been drawn, it is time to determine how to implement the design. Many of these decisions come down to whether to use standard components or more specialized components. Standard components are readily available, they are often more affordable, and their reliability is a known quantity based on many years of test and analysis. On the other hand, one specialized component can often replace multiple standard components. This reduces the PCB’s footprint and the time that it takes to design a circuit. Whether it’s a high volume Class 1 design like an affordable CF (Compact Fluorescent) light bulb circuit, or a small run Class 3 Mil-spec power supply requiring a FMECA report (Failure Mode Effects and Criticality Analysis report), your components can dictate the success of the board. While it’s tempting to choose the latest, fastest microprocessor or the voltage regulator with the most features, you’ll need to consider whether these features will actually help make your board successful. For example, these IoT devices come with excellent hardware, but their price tags exceed their practicality. Be prudent, you don’t want to end up like the Juicero Juicer.

 

Word “Expenses” being cut in half
Choosing standard components can help lower your expenses.

 

 

Specialized components can become standard over time

Discretion is key when using specialized components, which also means that picking the right ones can pay off in the long term. Over time, some specialized components will evolve into standard components. This means that it’s important to keep an eye on the market in order to stay competitive. In the case of the CF light, the main reason to choose standard parts is affordability. Still, specialized components are becoming more and more common in these circuits. For example, the CFs tiny ballast coils regulate power using discrete components that generate a high speed switching signal are beginning to be replaced by integrated circuits. These components include features that reduce radio frequency (RF) noise, improve power factor correction (PFC), and can even include dimming functionality. This makes for competitively priced products that have superior performance and a faster design time.

 

Rules, Regulations, and Choices

Designs for military use, like our hypothetical Mil-Spec power supply, require certain components to have reliability specifications. For example, Mean Time To Failure (MTTF). Components in this design have an effect on the reliability rating of the entire assembly, which must meet certain overall criteria. Component selection in these situations is critical for meeting the basic design requirements. There is a broad array of standard components that meet these well-tested specifications, but using them can mean using more components. This can result in more potential points of failure. Sometimes system redundancy requirements can make using specialized components a necessity. In these cases, using specialized components means finding designs from manufacturers that have gone through the painful process of being validated, and may or may not be readily available for the next production run. Since meeting these stricter criteria takes a lot of work, manufacturers will try to keep these components on the market for as long as possible. However, there are no guarantees. There is an entire industry based around providing obsolete Mil-Spec components, and you better believe it’s for a price.

Good Help Makes Great Things Happen

 

“Rules” and “Regulations” marked on stamps
The right components can help you meet design regulations.

 

 

While component selection varies on a case-by-case basis, these guidelines provide a general idea of when you should opt for more specialized components, or stick with the cheaper standard ones. At the end of the day you’ll need to start somewhere, and wherever that is, having BOM tools like the ones Altium provides can be a massive help in sorting through your alternatives. Historical data for both part pricing and part availability conveniently put real data in front of you to help make those big decisions at the start of a design. Customizable access and permissions for your BOM in the cloud makes team collaboration on these decisions easy, and real-time price information keeps estimates up to date as the process evolves. When it’s time to build the first prototype, Altium’s BOM tools can even automatically populate shopping carts, saving time and reducing errors in the purchasing process.


Have a question about specialized or standard components? Contact an expert at Altium.

About the Author

Altium Designer

PCB Design Tools for Electronics Design and DFM. Information for EDA Leaders.

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