How to Handle Obsolescence in Legacy Designs

At some point, every product will become a legacy product, it’s just that this transition takes longer for some electronic devices. As a system ages, its components also age and will eventually be replaced with updated versions. In some instances, some of the most important components in a product will go end-of-life (EOL) and will be discontinued. Suddenly, when it’s time to produce a new batch of the product, the manufacturer finds multiple components are out of stock, obsolete, or totally discontinued.

How can a company continue supporting these products when they might face large parts of their BOM going obsolete? If your product will see continuous use and sales over a significant time period, then it can be difficult to see the future and create a long-term plan for obsolescence management. Fortunately, if you know what data to watch for, you can take an agile approach and react quickly to lifecycle changes for your components.

Obsolescence Planning on Different Time Scales

Practical planning for obsolescence in electronics can be very difficult, which is why the agile approach may be preferable over a rigid approach to holding inventory and design refreshes. To illustrate what obsolescence timeframes your company might need to consider, take a look at the table below. In this table, we have three broadly categorized timeframes where different obsolescence challenges can arise. In general, as time goes on, the chances that a product will need a total design refresh will increase.

Obsolescence timeframe & What to expect

Short-term (<5 years)

• Plan to fully support the product with repairs, field service, etc.
• Main ICs unlikely to be marked obsolete/EOL
• If PDNs received for main ICs, plan for a design refresh

Moderate-term (5-10 years)

• Expect more of the main ICs to go obsolete/EOL
• Plan for at least 1 product refresh over this time frame
• Many products will be retired within this time frame, some will need plan for long-term support

Long-term (10+ years)

• Plan to retire support for existing product
• Most main ICs will be updated to new packaging or go EOL
• Product will most likely need a major refresh or new product introduced

End-of-life

• Fully retire support for existing product
• If there is continued demand, introduce entirely new version
• Re-engineer the product architecture.

The exact definitions of short, medium, and long term vary by product and industry, so the above time frames are not set in stone. For example, in consumer electronics, entire products (not just components) are typically obsolete a handful of years following release to market, and consumers should not have a realistic expectation of support (warranties) beyond this time frame. In a commercial setting, or in a high-reliability area like mil-aero, products will have decades-long lifetime requirements and parts will have high risk of obsolescence.

Simple Ways to Anticipate Legacy Obsolescence

Because no design team can predict the future, the key is to take an agile mindset and have contingencies in place to react to inevitable obsolescence in legacy products. Information and feedback to a design team is key to managing obsolescence in electronic products. While no company has the perfect process for dealing with every obsolescence and supply chain issue, there are some simple strategies that can help ease product management throughout the product’s lifecycle:

• Subscribe to lifecycle notices - Some design platforms, distributors, and supply chain platforms will provide notifications of lifecycle changes for components in your product’s BOM.
• Subscribe to PDNs - Product discontinuation notices can be obtained from supply chain intelligence platforms or directly from semiconductor manufacturers.
• Inventory management - Prioritize a common set of parts and suitable replacements to ensure repeated production, at least through a short-term timeframe.
• Identify replacements early - If you know about suitable replacements for the main value-creating components, you can prioritize these in design refreshes as your product ages.
• Stagger product refreshes - Plan for periodic refreshes as the most important parts in the design go obsolete or EOL.
• Create watchlists - Some supply chain tools (including free sites and distributors) have a watchlist feature; you can enable this to get detailed information about the most important parts in a product.

Which parts should be the main drivers of design refreshes to support a legacy product? Again, the answer varies by industry and product, and even based on the parts that appear in the product. You don’t need to have watchlists and PDNs for every single resistor or capacitor in the design; focus on tracking the main value-creating components and have contingencies in place for when these parts go obsolete.

With an approach that targets the components creating the most value, your design team can prioritize design refreshes as they arise. Design teams don’t need to implement every change directly in the source files as parts go obsolete, but instead the product’s design status should be documented and designs updated between larger production runs.

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