A lot of components do the same thing. How do you choose the best one?

The decision to use one component over another in your product or system design can often be tedious, especially when many parts from different suppliers appear to have the same specifications. While flipping a coin can seem like the easiest way to go, there are better strategies available to assist in your evaluation process.

You could develop a simple decision table to help you choose one part over another. For example, the most rudimentary one might include Features, Price, Quality, and Availability as the component qualifiers. Then, making an educated assessment on each, you assign a score of 1 to 5 to each part for each of the 4 qualifiers. Finally, add up the scores and go with the winner.    

Alternatively, you could also do a quick search for help on-line. This will yield numerous posts from many suppliers on how to select the best components. The recommended evaluation and selection process that they typically offer usually includes the following steps:

• Determine the function of the part you need for your design
• Define your technical requirements for performance of the part (power needs, output, form factor, thermal envelope, mounting style, etc.)
• Determine any additional needs (Hi-Rel, MIL-SPEC, technical standard specifics or regulatory needs that cover a specific application, etc.)
• Research available components in the market
• Develop an applicable part/supplier list 
• Test and verify each potential part (in-circuit if possible)
• Determine price vs. quality trade-offs for each part
• Assess current availability and future deliverability for each part
• Cut the purchase order to the winning supplier

That may sound like a fairly complete set of the steps to take, and many of them you probably know about. They run in a logical succession from need to solution. If you pattern your selection process after this you probably will not go wrong, even faced with very similar components. Of course, you will also have to decide on a metric to assess quality, determine your timeframe for part availability, and predict if you can source the part going forward.

Additional Specifics You’ll Need to Know

The reality of the component sourcing process, however, is that the selection of components, even those that appear to be specification-identical, is often determined by other factors that may vary by company, project, or the personnel involved in the decision making. If you are working for a large enterprise, component selection may be determined via a set policy that you will have to follow. If you are part of a smaller operation, you may be developing the process yourself.

In either case, here are a few additional considerations that you may need to keep in mind as you move forward in the component selection process. All of them may not apply to your individual situation, but some of them will. And the answers to them may help you decide between two similar parts. These additional questions to answer are:

• Does the manufacturer offer good documentation? At first glance this seems like a universal requirement, but documentation can vary widely by company or region. Documentation requirements on components used in a product will be different and heavily dependent on the industry and application.

• How soon can I get samples to build a prototype of my design? When you are advancing to the breadboard stage, you need working component samples today. Your ability to obtain samples will vary by supplier, and whether or not they have a sampling program.

• Does the part need to be on the QPL?  A Qualified Parts List (QPL) is a list of components, products, or materials that have met the applicable specific requirements established by an organization or governing body. Qualification typically involves rigorous testing, inspection, audit, and documentation. QPLs are commonly used in Aerospace, Telecommunications, and Electronics, and are mandated by the U.S. Department of Defense. 

• Does the supplier need to be on the QML? A Qualified Manufacturers List (QML) is a list of manufacturers who have had their products and processes tested and met applicable requirements as established by an organization. 
• Does your company have an approved vendors list? Theoretically, this could be the same as a QML, but may be limited to suppliers with whom you simply have a purchasing agreement covering part quantity or pricing. For example, if your company has a contract to purchase a certain amount of a connector from a certain company, and is not reaching that level, sourcing of the part that you need may be used to fulfill the other agreement.  The parts you want to source may need to be on this list if your company maintains one.
• Can the various suppliers deliver parts at the scale you may need? Even though two parts may have the same specifications, the two different manufacturers may or may not be able to meet the component demand you anticipate. This is where honest communication with a reliable supplier trumps price.

• Are there regulatory or standards requirements covering part use that are country or region-specific? Standards or regulations covering the use of the components that can be used in a product or system can vary from country to country. Just because the components you want to use are approved for the U.S. market doesn’t mean they will be accepted for offshore markets.

• What is the probability of a part becoming obsolete or reaching EOL status? This is a question you should be routinely asking of every supplier you deal with, including component distributors. An unanticipated End-of-Life (EOL) notice can mean substitution problems for your manufacturing supply chain, and potentially force you into a redesign.

• Does your company have an existing purchasing relationship with a supplier? Depending on the product, market, or application, component sourcing may be part of a purchasing relationship based on history or contract that can affect your ability to use a specific part from a different manufacturer.  

• Can the use of a branded component add value to my product or system? The use of branded parts in a product or system may serve to add marketing value to what you are selling. By suggesting high reliability or sophisticated design, two identical parts may be differentiated merely by their branding.

• How do you assess the marketplace reputation of a supplier? This is a particularly challenging question but if you are trying to decide between part A or part B, the reputation of the manufacturer may play a large role, externally and internally. A more attractive price for an identical product from an offshore supplier may not be helpful when failure rates start to climb on your production line.  Reviews may be the best option but, depending on the resource you’re using to purchase the parts, you may need to look externally to find what experiences others have had with a particular supplier.

Conclusion

Sourcing of the components you need for a design is not as simple as ordering from a catalog, especially if you are anticipating a ramp-up for production. More often than not, two components that appear to be identical are far from it, when other factors are considered. Navigating your way through the part selection and sourcing process can be made easier by working with a qualified component distributor who has knowledge of many different parts, suppliers, relationships, and product history.

To learn or review the basics of many electronic components and learn about some of the more subtle differences that can be found between seemingly identical parts, you can visit our friends at CircuitBread, and view their many posted tutorials, study guides, and component references. You can also check out their take on this topic here: How to Choose the Best Components When You Face Similar Choices?