Last-Time Buy (LTB)
Definition
Last-Time Buy (LTB), sometimes called a last-time purchase, is the final order a buyer places for a component before the manufacturer ends production. An EOL notice opens the LTB window, which is usually around six months, during which buyers must place their final orders.
Why it matters
The Last-Time Buy is a forecasting bet with real consequences. You are ordering, in one shot, all the inventory you will ever get from the manufacturer for that part. The order has to cover remaining production plus spares and service demand across the product's full lifetime.
Get it wrong in one direction and you run short later, forcing a costly redesign or a scramble through the secondary market. Get it wrong in the other direction and you have tied up cash in inventory you may eventually scrap. This is why an LTB decision leans on demand forecasting, and why teams prefer to see it coming through NRND status well before the window opens.
Related terms
- EOL (End of Life): the notice that opens the LTB window.
- NRND (Not Recommended for New Designs): the earlier warning that an LTB is coming.
- PCN (Product Change Notification): how the discontinuation is formally communicated.
If a Last-Time Buy fell short, or you missed the window entirely, 3E Technology indexes the brokers and surplus dealers that hold post-production inventory. See sourcing obsolete electronic components.
Frequently Asked Questions
What is a Last-Time Buy?+
A Last-Time Buy (LTB) is the final order a buyer can place for a component before the manufacturer stops production. It is triggered by an End-of-Life notice, and the window to order is typically around six months. The order is meant to cover all remaining production and service demand for that part.
How do I size a Last-Time-Buy order?+
Forecast the total remaining demand across the product's expected lifetime, including production, spares, and warranty or service needs, then add a margin for uncertainty. Ordering too little means a future shortage and a possible redesign; ordering too much ties up cash and risks scrapping excess. Accurate demand forecasting is the hardest and most important part.
Related Resources
EOL (End of Life)
EOL, or End of Life, is a manufacturer's notice that a component will stop being produced. Here's what it means for sourcing and how to respond.
NRND (Not Recommended for New Designs)
NRND means a manufacturer is phasing out a component: still available, but not for new designs. Here's what the status signals and how to react.
PCN (Product Change Notification)
A PCN is a manufacturer's formal notice of a change to a component, from a process tweak to discontinuation. Here's what PCNs cover and why to track them.
How to Source Obsolete Electronic Components: A Practical Guide
When authorized distributors run dry on an EOL part, here's the workflow for finding inventory, vetting suppliers, and avoiding counterfeits.
Find the suppliers you need
Search 105,000+ vetted parts suppliers in one query. Free tier includes 5 unlocks — no card required.
Start searching