Checking a chip's longevity before designing

The schematic is half done and someone asks the question that should have come first: how long will this microcontroller be buildable? The datasheet does not say. The distributor page shows stock today and nothing about next year. The honest answer is in a vendor policy document that almost nobody opens until the discontinuation notice has already arrived.

We have written before about what to do when a microcontroller goes end-of-life. This note is about the step before that: reading the longevity programs the major vendors publish, understanding what each one does and does not promise, and turning that into a part choice that will not need a redesign in year three. With the Cyber Resilience Act putting a legal support period on connected products, the buildable life of the silicon is no longer only a purchasing concern.

What the programs actually say

Every large vendor has a longevity page, and they are less alike than they look. The differences matter when you compare candidates.

STMicroelectronics runs a rolling commitment for the STM32 family. A part in the program carries a badge on its product page reading “10 years longevity commitment”, and the product longevity page lists each part number with an “available until” date. ST’s own how-to article explains the mechanism: the date is the current year plus ten, and it is renewed annually for as long as the part stays in the program. So a badge seen in 2026 means orderable until early 2036, and next year the same part should read 2037. The thing to watch is the opposite case. If a part’s date stops advancing, ST has quietly decided not to renew it, and that is your earliest warning.

NXP publishes a table rather than a badge. Its Product Longevity Program states that “the minimum period is either 10 or 15 years” and that “product availability is measured from NXP’s launch date of the participating product”. That last clause is the one people miss. A part launched twelve years ago with a ten-year term has already used its commitment, even though it is still active and in stock. The table lists launch date and expiration date per part number, so the arithmetic is easy once you know to do it.

Texas Instruments takes a different approach. Its product life cycle page defines five statuses, from Preview through Active, Not Recommended for New Designs, Last Time Buy and Obsolete, and states that “TI’s product life cycles are typically 10 to 15 years and often extend longer.” Rather than a per-part date, TI lists conditions under which a standard product is not eligible for obsolescence at all: recent sales activity, less than ten years in production, or existing customer demand. That is a policy about behavior, not a dated promise, and it should be read that way. The status field is the actionable part. A part marked Not Recommended for New Designs is still orderable, but TI has told you its future in plain words.

Microchip frames its practice as customer-driven obsolescence. Its published end-of-life policy ties continued availability to ongoing business activity and manufacturability rather than a fixed term. That is reassuring for mature PIC and SAM parts with steady demand, and it is why Microchip is often the vendor of choice for products that expect a long tail. It is also not a date, and a part with no orders for a few years is exactly the kind that can be discontinued.

Nordic Semiconductor is the most informal of the five. Its general announcement on long-term parts availability says the objective is to maintain supply as long as there is market demand, and that discontinuance will be communicated under the JEDEC J-STD-48 provisions. For a nRF52 or nRF54 design that is a statement of intent, not a commitment with a year attached.

Vendor	Form of commitment	Where to check
ST	Rolling 10-year date, renewed yearly	Badge on product page, longevity table
NXP	10 or 15 years from launch date	Longevity program table
TI	Status plus eligibility conditions	Product page status field
Microchip	Demand-driven, no fixed term	EOL policy, PCN subscription
Nordic	Demand-driven, J-STD-48 notice	General announcement

What a commitment does not cover

A longevity program is a promise about ordering the silicon. It says nothing about three things that end product lives just as effectively.

The first is the package. A vendor can keep a die in production for fifteen years and still drop one package variant of it, because a package is a separate line item with its own volume. When you check longevity, check it for the exact orderable part number, including the package and temperature grade you intend to buy, not the family.

The second is the silicon revision. A part can stay on the longevity list through a die shrink that changes its analog behavior, its errata list or its flash timing. The commitment is real, but your firmware may still need to be requalified against the new revision.

The third is the toolchain. In a June 2026 ST community thread about STM8 and STM32C0 longevity, the most useful reply was not about the silicon at all. It pointed out that an abandoned compiler or debugger is a practical end-of-life regardless of the availability date. STM8 is the current example: parts may be orderable, but the development tools are not being carried forward the way STM32 tools are. A part whose only toolchain is a single vendor IDE is a riskier choice than one supported by GCC and an open debug stack, even when the longevity dates match.

The checks before a part goes on the schematic

These take under an hour for a short list of candidates and they save a redesign.

1. Find the exact orderable part number and look it up on the vendor’s own page, not only the distributor’s. Record the status, the longevity badge or table entry, and the date you looked. A screenshot in the project notes is enough.
2. Do the launch-date arithmetic. For a fixed-term program, subtract the launch year from the expiration year and note how much of the term is already spent. Prefer a part early in its term over an equivalent part late in it.
3. Read the status field literally. Active means active. Not Recommended for New Designs means the vendor has told you not to use it in a new design, and there is no version of that sentence that a buyer will accept in a review two years from now.
4. Check the package line, not the family. Search the vendor’s PCN archive for the family name and look for package discontinuations in the last few years. A family that has been shedding packages is telling you something.
5. Subscribe to the PCN feed for every part on the BOM that matters, at the vendor, in the name of a role mailbox rather than a person. Every vendor above offers this. The notice arrives months before last-time-buy, and only if someone is registered to receive it.
6. Ask about the toolchain in the same breath. Is there a GCC target, an open debug protocol, a maintained HAL? If the answer is a single proprietary IDE, weigh that against the longevity date rather than beside it.
7. Name a second candidate now. Not a drop-in, which rarely exists, but a part in another vendor’s family with a similar peripheral set, chosen while the design is still fluid enough to keep the layout compatible where it is cheap to do so.

The trade-off is real. The part with the strongest longevity story is often not the newest, the cheapest or the lowest power. A ten-year-old STM32F1 with a rolling ten-year badge is a safer bet on buildability than a part launched last year with no badge yet. Which one is right depends on how long the product has to ship, and that is a question for the person who owns the product, not the engineer picking the part. The point of running the checks is to put that question on the table before the schematic is done rather than after.

What the notice period buys you

When a discontinuation does come, the JEDEC discontinuance standard that most vendors reference sets minimum windows for placing final orders and for taking final delivery. Individual vendor policies state their own windows in months, and they are not generous. The window is enough to place a lifetime buy if you already know your volumes, and enough to start a redesign if you already have a second candidate. It is not enough to do the analysis from scratch, which is why the checks above belong at design time.

We run this check on every microcontroller, radio and power part before it goes on a schematic we draw, and we record the result in the design notes so it can be re-read a year later. If you have a BOM you are not sure about, send us the part numbers and the expected life of the product, and we will tell you which ones need a second look.