Avoid the pitfalls of obsolescence

10 APRIL 2015

The market for electronics components has changed radically over the past three decades. The driving force in terms of component volume is now the consumer market and no longer applications such as mainframe computers or military and industrial systems. Almost two-thirds of global sales now are into the PC and mobile-telephony markets, which are heavily consumer driven.
The focus of the consumer markets is to maintain a rapid pace of development in which manufacturers attempt to take full advantage of the advances in process technology that

occur typically on a two-year cadence. Components made on what was the most advanced process two or three years ago are quickly rendered obsolete by their replacements. Because most of the products that these devices go into have an even shorter average shelf life, this constant renewal is not a problem.

Author: Dave Doherty, VP Global Supplier and Product Operations, Digi-Key

For users in industrial markets, the replacement cycle of many modern integrated circuits (ICs) has become increasingly problematic. Although dedicated industrial-grade parts, such as those qualified for extended temperature ranges, will generally be supported for more than ten years by IC manufacturers, other systems within the vehicle that do not need the environmental support of industrial market-focused components will often use consumer-grade parts as they offer a high performance-cost ratio or simply are the only components available with the required computational, bandwidth or signal-processing performance.
Manufacturers of medical systems often have to face the problem that, by the time they have succeeded in obtaining regulatory approval for their systems, suppliers will already has classified the parts they depend on as mature.
Memory ICs tend to be highly vulnerable to short-term shifts in supply strategy. Parts designed for memory buses that were state of the art five years ago are now regarded as legacy designs, with all but specialist manufacturers choosing to focus on more recent bus interfaces such as DDR4 or LPDDR3.

In many cases, manufacturers will announce the end of production with a last-time-buy announcement, which may only arrive six months before manufacturing on that product ceases. The decision that the user needs to take at this point is to work out whether sourcing an alternative is viable and, if not, if there is a requirement to place a last-time buy. The user needs to work out how many they are likely to need to continue to support their products to cover their own lifetime-support commitments.
If they wait and miss the deadline, they need to find other ways to source spare parts, which may be through the grey market. Manufacturers will often place device stock they no longer need onto the grey market in order to recoup some of their expenditure. Unfortunately, the grey market is the way in which many counterfeit products enter the supply chain.
Distributors can help with the situation of monitoring the supply situation and provide advance warning of last-time buys and of the signs that may indicate that a manufacturer will want to suspend production. Digi-Key, for example, sends out obsolescence notifications to customers for parts they have bought previously to ensure they are updated on supply status.
A last-time buy can introduce further issues as some procurement policies are designed to reject products with old date codes. As the target product ages, components bought on a last-time buy will often have date codes that will be too old to fit with this policy.
If a part has gone into its end-of-life phase and the user has missed the last-time-buy deadline, other options may be available. Devices that experience lower sales volume than other parts within a family are more likely to face the end of production more quickly. In many cases it is possible to replace the obsolete part with one that is a near-match, often with minimal redesign.

For example, a replacement microcontroller may have more onchip peripherals than the original part but will, when it runs the same software, demonstrate the same behaviour.
The technical department within a distributor such as Digi-Key can provide valuable advice on form and fit compatibility for many parts.
The long-term answer to obsolescence issues is to plan for the eventuality and build procurement strategies around components and families that have supply guarantees. To try to provide customers with long lifetime requirements, some semiconductor manufacturers will commit to longer support cycles for a selected group of their parts.
For example, Intel sells a range of PC-compatible processors that are standard parts but, so that they can be used in long life-cycle industrial applications, has earmarked some products as being supported and sold for ten years or more from initial production. This information provides users with high confidence of supply when they design the parts into their systems.
Franchised distributors are vital sources of information in the design phase by indicating to users which parts are supported under long life-cycle plans. Digi-Key, for example, has extensive experience of advising on the medium- to long-term supply scenarios for the components they provide.
Customers can provide a bill of materials and experts will check the document for parts that are at risk of going end-of-life.
In some cases, it is impossible to avoid using a part with a high risk of obsolescence because it offers key features not available in competing parts. In those cases, franchised distributors such as Digi-Key can set up contracts in which, in exchange for a commitment on the number of components needed during a product’s lifetime, they will arrange that number to be made available and stocked in the warehouse and released for manufacture as needed like any other device.
Changing the product-design strategy to accommodate obsolescence is another approach that users can adopt. This strategy assumes that a number of the parts in the original design are likely to become obsolete during the product’s life-cycle. It involves planning component purchases such that they can be replaced more easily by similar parts and accommodate technology insertions that may involve changes in package type and device speed. By designing products such that they can take form and function compatible replacements, it is possible to reduce the risk of being subject to supply problems caused by the obsolescence of a single component.

For example, the use of programmable solutions provides a way to future-proof key elements of a design. Programmable solutions are often designed in such a way that they can provide a high degree of assurance over form, fit and function for replacement products. Even though the manufacturers may retire older parts in favour of those built on newer processes, the same design will easily move to the replacement parts, which can often be obtained in packages pin-compatible with the originals. The design tools are built in such a way that a design ported to a later, more capable part will in most cases behave as it did in the older product.
Similarly, choosing microprocessors and microcontrollers that use industry-standard architectures available from multiple vendors can provide a greater degree of protection against obsolescence than a product line that may be available from only a single manufacturer. Although finding a direct match for a microcontroller from another supplier’s range may not be possible, changes to the design and software may be minimal as such parts often provide similar features and peripherals.
The only change may be to device drivers to ensure that the peripherals are mapped to the correct areas of memory for the application. Microcontrollers with on-chip programmable logic and analogue peripherals have proven to be the answer in a number of cases when fixed-function parts have disappeared from the market.
Replacing a dedicated part with the programmable solution involves greater design and integration effort but, in an industry prone to sudden obsolescence, it provides an effective way of managing the problem for key parts of the system.
Even with effective design strategies, obsolescence remains an issue that faces many users of electronics components. But with the help of supply-chain partners who can advise on potential alternatives and keep customers informed of trends in production, it is possible for companies to stay on top of the problem.

www.digikey.com

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