EOL, PCN, PDN: Decoding the Notices
An email arrives from a manufacturer with a string of acronyms and a couple of dates. Buried in it is a deadline that can quietly strand a part your product depends on. Here's how to read it — and act before the window closes.
End-of-life notices are easy to skim past. They arrive routinely, they're written in acronyms, and the date that matters is usually buried in a table. But miss the wrong one and a part you've designed in becomes unbuyable through normal channels — on a deadline you didn't choose. The first defense is simply knowing what each notice is telling you.
The Acronyms, Decoded
- PCN — Product Change Notification. The manufacturer is changing something: process, materials, package, or lifecycle status. Not always end-of-life, but always worth reading, because some changes require requalification.
- PDN — Product Discontinuance Notification. The part is being discontinued. This is the notice that starts the clock.
- EOL — End of Life. The part has reached the end of its production lifecycle.
- LTB — Last-Time Buy. The final date to place an order before production stops.
- NRND — Not Recommended for New Designs. Still available, but on notice — don't design it into anything new.
The Typical EOL Timeline
A discontinuance usually unfolds in a predictable sequence. The exact intervals vary by manufacturer, but the shape rarely does:
- PDN issued — the notification goes out, naming the affected part numbers and the key dates.
- Last-time-buy window opens — a defined period to place final orders.
- LTB date — the hard deadline. Miss it and the factory will not accept another order.
- Last ship date — the manufacturer fulfills final orders, then production ends for good.
The gap from PDN to LTB is often measured in months, not years. That's short enough that a notice sitting unread in a shared inbox is a genuine supply risk, not a paperwork formality.
What to Do When One Lands
Three questions, answered quickly, tell you almost everything:
- Do we use it? Cross the affected part against active BOMs and anything in the design pipeline.
- For how long? Estimate remaining product life and demand — that's what sizes the decision.
- Buy, bridge, or redesign? Place a last-time buy to cover the full horizon, bridge with a smaller buy while you qualify a replacement, or redesign around the part now.
Sizing a last-time buy is its own discipline — over-buy and you sink capital into aging stock; under-buy and you're back on the open market in two years. We cover that math in our last-time-buy strategy guide.
Got a PDN on a part you can't requalify yet?
Send us the part number — we'll check availability for a bridge or last-time buy.
If You Missed the Window
It happens to careful teams — notices slip through, forecasts come up short, products outlive their plan. Once the LTB date passes, the part exists only on the secondary market. That's where an independent distributor takes over: locating remaining worldwide stock, authenticating it, and shipping it with traceability so a missed date doesn't become a stalled line.
RH Electronics has sourced obsolete and post-EOL parts since 1982. Search our catalog or submit a requirement.