PCN and EOL Management: From Notice to Last-Time Buy

A product change notification is a date with a deadline. The work is not reading it — it is deciding whether the part still fits, and how many to buy before it becomes unavailable.

1. What a PCN actually changes

The standard reference is JEDEC JESD46 (product change notification) and JESD48 (product discontinuance). They define what a notice should contain and how much warning is expected. A supplier that does not follow them is not necessarily unsafe — but you are then relying on their process rather than a common one.

Where notices actually arrive: distributor lifecycle portals, supplier email lists, and the occasional PDF attached to a sales call. A register that depends on someone forwarding an email is not a process. Subscribe to the portals for the parts on your BOM, and reconcile the register monthly against the last-time-buy list.

The register is also how you answer the question "which of our products are affected?" — a part-centric list is useless if it cannot be joined to the BOM.

2. The EOL timeline

Typical notices give months, not weeks. That window is for engineering, not procurement: if the part must be replaced, the replacement has to be qualified before the last-order date, otherwise the last-time buy has to cover the design change too.

A typical sequence: notice in January, last order in September, last shipment in December. That is eight months to qualify an alternative — enough for a drop-in second source, tight for a layout change, and not enough if the replacement itself needs a new certification.

Two dates matter and are often confused: the last order date (when the PO must be placed) and the last ship date (when the supplier stops shipping). Buying on the ship date is too late.

3. Impact assessment

A practical rule: if the change touches the die or the package, test in the product. If it touches only marking or the datasheet layout, a documentation update may be enough. The middle cases — assembly site, test site — are where most organizations under-test.

Three test levels are usually enough: a datasheet check for documentation-only changes; a bench check of the affected parameter for site or material changes; and a full application test (temperature, EMC, life) for die or package changes. Write down which level applies before the review meeting, so the decision does not drift toward "we already have stock".

4. Last-time-buy quantity

Annual demand 12,000
Coverage: 2 years production + 0.5 year service
Buffer: 15 % for yield and forecast error
Current stock: 3,000

LTB = 12,000 x 2.5 x 1.15 - 3,000 = 31,500 pcs

That number is a forecast, and it should be labelled as one. The temptation is to round up "to be safe"; the cost is inventory that may become obsolete when the redesign lands.

A useful comparison: the cost of qualifying a replacement against the cost of carrying the LTB stock. A $20,000 qualification that removes 30,000 pieces of inventory is often cheaper than the inventory itself — and it removes the future risk entirely.

Example: 30,000 pieces at $0.40 is $12,000 of inventory, plus storage and the risk of scrapping it if the product is discontinued first. A $20,000 qualification looks expensive until the inventory is written off; the two numbers are the same order of magnitude, and the qualification keeps paying after the stock is gone.

Whatever is decided, write the basis: forecast used, coverage years, buffer, and who approved it. A round number with no basis is impossible to defend in an audit or a post-mortem.

5. The process, in one page

1. Register: every PCN gets an ID, a part, a date, and an owner — not an email folder.
2. Assess: form, fit, function, process; decide whether testing is needed.
3. Test: appropriate to the change; document the result.
4. Buy: LTB quantity with a written basis, not a round number.
5. Record: update BOM, AVL, inspection criteria and the product file.

If step five is skipped, the same PCN comes back in two years when someone finds a part in the BOM that no longer matches the drawing.

The record should also capture the disposition: accepted as-is, accepted with a note, or rejected with an alternative. A rejected PCN with no alternative is a supply risk that belongs on the same list as an EOL notice, because the next notice may be the discontinuance.

5b. The inputs to the LTB number

6. Red flags

For parts already in stock, the MOQ and partial-reel guide covers how much to buy and how to store it; for the assembly side, the incoming inspection routine covers how to verify the last-time buy when it arrives.

7. FAQ

What is the difference between a PCN and an EOL notice?

A PCN announces a change to a part that continues to be produced. An EOL notice announces that production will stop, with last-order and last-ship dates.

Do I need to re-qualify for every PCN?

No. Re-qualification is proportional to the change. Marking changes need documentation; die changes need application testing.

How far ahead should I plan a last-time buy?

Cover production plus service plus a buffer, and check the number against the redesign timeline. If the redesign lands sooner, buy less.

What if I miss the last-order date?

The part moves to the independent market, with the risks covered in the counterfeit and MOQ guides. Budget for testing and expect higher prices.

Should I keep a sample of the old part?

Yes, a small retention sample per lot. It answers "did the change actually change the part?" without relying on photographs.

What if the supplier offers a replacement with a different pinout?

That is not a replacement, it is a board change. Treat it as a design project with its own timeline, not a procurement substitution.

Who owns the PCN process?

Usually quality or procurement, with engineering as the assessor. The important part is that one named person owns the register.

Are PCNs legally required?

Not universally, but JEDEC JESD46 defines the industry expectation. Most authorized distributors pass them through; the buyer has to act on them.

8. Sources

• JEDEC, JESD46 — product change notification (content and process expectations).
• JEDEC, JESD48 — product discontinuance (EOL notice and last-time-buy practice).
• JEDEC, JEDEC standards index — current revisions of the above.
• Supplier PCN portals and distributor lifecycle tools — where the notices actually arrive.