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Electronic Component Lifecycle Status Reference (NRND, LTB, EOL)

Lifecycle labels are used loosely across datasheets, distributor sites and aggregators. This reference explains what each common term usually means and what you should do about it, so a status change on a BOM line leads to the right action.

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Status or term	Typical meaning	Typical buyer or engineer action	Notes
Preliminary / Pre-release	Part announced or sampling, specification may change	Engineering only; do not commit to production volume	Datasheet may be marked advance or preliminary.
Active / In production	Manufacturer is producing and selling the part	Normal purchasing; watch lead time and change notices	Active does not guarantee a long future life.
Mature	Production continues, no new features expected	Safe for new designs with periodic checks	Not used by every manufacturer.
NRND	Not recommended for new designs	Do not select for new designs; plan a migration and consider a buffer	Usually precedes end of life but timing is not guaranteed.
Last time buy (LTB)	Final window to order before production stops	Compute lifetime demand, secure budget, place the order before the deadline	Deadlines are firm; orders are often non-cancellable.
Last time ship (LTS)	Final date the manufacturer will ship the part	Confirm delivery schedule against the LTB order	Often later than the LTB date.
Lifetime buy	Purchase of the estimated remaining lifetime requirement	Include forecast, spares, field repair and warranty demand	Over-buying creates excess; under-buying forces redesign.
EOL / End of life	Manufacturer has decided to stop production	Open an obsolescence case; review alternates, LTB and redesign	Wording differs; check the formal notice.
Discontinued	Part is no longer produced	Source remaining stock only through authorized channels first	Often interchangeable with EOL in listings.
Obsolete	No longer available from the manufacturer	Aftermarket, authorized remanufacture, substitute or redesign	Independent market carries counterfeit risk; test and verify.
PCN	Product change notification for form, fit, function, process or site changes	Review the change, assess impact, respond within the notice period	JEDEC JESD46 describes notification practice.
PDN	Product discontinuance notification	Trigger LTB analysis and alternates search	JEDEC JESD48 covers discontinuance notices.
Allocation	Supply is rationed by the manufacturer or distributor	Confirm commitments, forecast clearly and qualify alternates	Not a lifecycle stage but behaves like a risk flag.
Authorized aftermarket	Licensed supplier continues to make or supply a discontinued part	Evaluate for long term supply with proper traceability	Different from the open broker market.
DMSMS	Diminishing manufacturing sources and material shortages	Run a managed obsolescence process with monitoring and resolution	Term used in US defense programs.
Form fit function (FFF) replacement	A substitute matching form, fit and function	Qualify through engineering and update BOM and AVL	Customer approval may be required.

Manufacturers and data providers use their own labels and definitions. Always read the actual notice from the manufacturer and keep a copy. This reference is general guidance, not a substitute for the formal notice.

Flag at-risk BOM lines from your ERP

Optional: ask how lifecycle status could be tied to your BOMs and ECO workflow.

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How to use the table

Search for the term you see on a datasheet, a distributor listing or an obsolescence tool. The table gives the typical meaning, a suggested action for buyers and engineers, and notes on where definitions differ. Export to Excel and use it as the dictionary for your lifecycle field in the item master, so everyone applies the same status and the same response across engineering, purchasing and planning.

How the lifecycle usually unfolds

A typical path is pre-release, active, mature, NRND, then a discontinuance notice with a last time buy and last time ship date, then obsolete. Not every part follows this path, and timing varies from months to years. The key decision points are when you see NRND (stop designing it in), when you receive a PDN (calculate lifetime demand) and after LTS (shift to aftermarket, substitutes or redesign). Handle form, fit and function changes through PCN review and respond before the stated deadline or the change may be treated as accepted.

Include warranty and field service demand in lifetime buy math.
Ask for the last time buy terms in writing.
Check whether the manufacturer offers die bank or licensed continued supply.

Common mistakes and ERP notes

Teams often treat a distributor's lifecycle flag as authoritative when it may be a few weeks behind the manufacturer. Others ignore NRND until the part is hard to find. In ERP, store lifecycle status, last review date and the LTB deadline on the item or manufacturer part record, and report on all active BOM lines that carry NRND, EOL or obsolete parts. Connect the report to ECO triggers so an engineer owns each case. Never buy replacement stock from unvetted brokers without inspection and authenticity testing.

Frequently Asked Questions

What does NRND mean?

NRND stands for not recommended for new designs. The part is still manufactured, but the maker advises against using it in new products, usually because a replacement exists or the part is heading toward discontinuance. Existing products can continue to buy it.

What is the difference between EOL and obsolete?

EOL means the manufacturer has decided to stop making the part, often with last time buy and ship dates. Obsolete usually means it is no longer available from the manufacturer at all. In listings the terms are sometimes used interchangeably.

When should I place a last time buy?

After you compute lifetime demand, check for qualified alternates and confirm the deadline and cancellation terms. Do it before the LTB date, since orders usually cannot be placed afterward. Include spares, field service and warranty needs.

What is the difference between a PCN and a PDN?

A PCN announces a change to the product, process or site and asks customers to review it. A PDN announces that a product will be discontinued. Both need a response plan, but a PDN triggers last time buy and redesign decisions.

If lifecycle status lives outside your ERP, we can help map it to item and BOM records so at-risk assemblies are flagged automatically. Optional; the table works on its own.

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