Obsolete and EOL RF Semiconductors: How to Keep Legacy Designs Running

The problem is not the part, it is the timing

Semiconductor vendors discontinue parts for rational business reasons: low volume, wafer-fab transitions, or a newer die. But radios, test equipment, industrial controllers and defence platforms stay in service for decades. The result is a widening gap between what is still needed and what is still made.

The warning signs

• NRND — Not Recommended for New Designs: still available, but plan for replacement.
• PCN — Product Change Notification: the vendor is changing or halting production.
• Last-time-buy (LTB) — the final window to order at factory pricing.
• EOL — end of life: only the open market remains.

Your options, in order of preference

1. Last-time-buy. If you can forecast demand, buy the remaining factory stock. It is the cheapest and safest route — but it ties up cash.
2. Authorised aftermarket. Some vendors licence continued production. Always the safest fallback.
3. Approved alternates. A pin-compatible or electrically similar part from another vendor, validated by test.
4. Open-market / broker sourcing. The spot market can find almost anything — with a risk premium you must manage.
5. Redesign. Often the only permanent answer; budget for it early.

Managing open-market risk

The open market solves availability but introduces quality risk. Reduce it with discipline:

• Buy from suppliers who can show the actual goods, not just a price.
• Verify the date code against the part's production history.
• For critical parts, request X-ray, decapsulation or functional testing.
• Start with a sample order before committing to volume.
• Keep records per lot so you can trace a failure back to its source.

Build a supply plan, not a purchase

Treat obsolete-part management as a programme: track lifecycle status across your BOM, forecast demand, and pre-qualify two or three reliable sources for the parts you cannot redesign. That way, when a line goes down, you are reordering — not searching.

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