STMicroelectronics
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A product-change email might seem harmless, but it could also disrupt your next production build without warning.
PCN, PDN, EOL, LTB, and LTS notices often show up together in your inbox, use similar wording, and hide important dates in attachments. Teams might treat them all as just 'supplier notifications,' only to find out too late that a part has changed, a last-time-buy window has closed, or a suggested replacement is not actually qualified.
| PCN | Product Change Notification | A manufacturer is changing a product, process, material, package, test flow, site, marking, or related controlled attribute | Changed material may affect qualification, assembly, reliability, or system behavior | Identify affected MPNs and evaluate the change |
| PDN | Product Discontinuance Notification | The manufacturer is withdrawing one or more products | Supply will end after the stated order and shipment windows | Calculate exposure and start alternate/LTB review |
| EOL | End of Life | A product has reached, or is entering, the end of its lifecycle | Future production, service, and repair supply may be lost | Confirm exact lifecycle dates and affected BOMs |
| NRND | Not Recommended for New Design | Product may still be available but should not be designed into new products | Future lifecycle and support risk | Stop new design-in; plan replacement |
| LTB | Last-Time Buy | Final date an order will be accepted | Missing the date may remove normal factory supply | Calculate demand and place an approved order before the deadline |
| LTS | Last-Time Ship | Final date the manufacturer expects to ship accepted final orders | Final supply ends after this date | Verify delivery, storage, and remaining support plan |
| EFSD | Estimated First Ship Date | Earliest date a PCN change may appear in shipped product | Old and changed revisions may both be encountered around transition | Control lot/revision traceability and qualification |
A PDN or EOL notice is different. It means the supplier plans to stop making the product. This is not just a process change; you have a limited time to decide on supply continuity, last-time-buy quantity, alternate qualification, or redesign.
PCN received?→ Ask: Can changed material enter our product without technical, quality, or customer impact?
PDN/EOL received?→ Ask: Can we support all production, service, and warranty demand before supply ends?
Not all changes carry the same risk. For example, updating a packaging label is very different from changing the die in a power MOSFET or moving assembly for an automotive IC.
Infineon states that major product/process changes affecting form, fit, function, quality, or reliability are communicated through a PCN process aligned with JEDEC J-STD-046. Infineon product change notification policy
Never assume a recommended replacement is electrically or mechanically identical.
Active↓NRND (sometimes)↓PDN / EOL Notice Issued↓LTB: Last-Time Buy deadline↓LTS: Last-Time Ship deadline↓Obsolete / no normal factory supply
Always use the dates given in the actual notice, not an assumed 12- or 18-month window.
Make sure every notification has a clear owner and is not left in a shared inbox. Follow this workflow within two business days.
| Packaging or administrative PCN | Low | Document and verify no customer-specific requirement |
| Manufacturing-site or material PCN | Medium | Review qualification and traceability impact |
| Die, electrical, test, or package PCN | High | Engineering validation and controlled transition plan |
| NRND | Medium | Block new design use; identify replacement path |
| PDN/EOL | High | Start LTB, alternate, and redesign assessment |
| PDN/EOL with no substitute | Critical | Escalate to engineering, procurement, quality, and program management |
Even if a capacitor has the same capacitance and voltage, it can still perform differently in a power supply due to ESR, ripple current, DC-bias loss, temperature behavior, or lifespan.
You should calculate your last-time buy carefully, not just estimate it.
[LTB quantity = (forecast production + service demand + safety stock) * BOM quantity per unit * (1 + yield allowance)]
A last-time-buy order might be non-cancelable and non-returnable. Make sure engineering, finance, quality, and supply chain all agree on the forecast and storage plan before you commit.
| Exact qualified replacement exists | Validate transition; avoid excessive LTB inventory |
| Pin-compatible replacement needs testing | Order samples; define validation timing; buy bridge inventory if needed |
| PCB redesign is needed | Calculate bridge demand through redesign qualification and ramp |
| No viable replacement and product support is long-term | Consider carefully calculated LTB plus controlled storage |
| Part is non-critical and product is near retirement | Avoid large LTB; manage remaining demand |
| Supply is only through unverified open-market sources | Escalate quality and counterfeit controls before purchase |
A supplier’s suggested alternative can be helpful, but it is not automatically approved for use.
| Form | Does package, footprint, height, terminal finish, pin count, and mechanical interface match? |
| Fit | Does it mate, mount, assemble, and thermally fit in the existing product? |
| Function | Does it meet electrical, timing, firmware, control-loop, performance, and reliability requirements? |
| Qualification | Does it meet AEC, industrial, medical, safety, or customer-specific requirements? |
| Supply | Is the alternate active, available, traceable, and less risky than the original? |
| Component engineer | Reviews lifecycle, notice content, qualification data, and technical risk | Identifies replacement path and lifecycle strategy |
| Hardware engineer | Evaluates electrical, firmware, thermal, and system impact | Approves alternate or redesign |
| Procurement | Confirms supply, pricing, LTB conditions, and delivery | Calculates order options and sources available supply |
| Quality engineer | Reviews qualification, traceability, supplier controls, and customer requirements | Approves open-market controls and alternate quality documentation |
| Manufacturing/EMS | Reviews assembly, test, yield, and lot-control impact | Confirms build schedule and remaining material usage |
| Program manager | Coordinates schedule, customer communication, and decision deadlines | Approves business tradeoffs, forecast, and escalation |
Manually checking your inbox can work if you have only a few suppliers, but it becomes unreliable as you add more products and manufacturers.
Treating PCN and EOL as the same event
A PCN might mean you need to qualify a change, but not make a buying decision. A PDN or EOL notice means you must decide on supply, and sometimes do technical work too. Follow the right process for each.
Assuming the recommended replacement is drop-in
Check the supplier’s own replacement notes, then complete form-fit-function and qualification review.
Waiting until LTB to calculate demand
The LTB date is your last chance to act, not when you should start planning. Reviewing forecasts, getting finance approval, and placing orders can all take weeks.
Buying a lifetime supply without a storage plan
Having too much inventory can cause problems like aging, moisture exposure, date-code restrictions, financial write-downs, and the risk that your finished product changes before you use up the stock.
Missing notifications because MPN data is incomplete
To monitor lifecycles effectively, you need the exact manufacturer part numbers. A generic description or an internal-only number won’t work.
Is a PCN the same as EOL?
No. A PCN announces a change to a product or process. EOL describes the end of a product’s lifecycle. A PCN can occur while a product remains active, although some discontinuance processes also use PCN tracking systems.
What is the difference between PDN and EOL?
A PDN is the formal supplier notice that a product is being discontinued. EOL is the lifecycle condition or process of reaching end-of-life. In practical purchasing terms, a PDN typically specifies the dates and conditions that initiate the EOL response.
What is LTB in electronics?
LTB means Last-Time Buy: the final date by which the manufacturer will accept orders for a discontinued component. Confirm the date, order conditions, MOQ, and final shipment date in the actual notice.
Does a recommended replacement mean it is pin-compatible?
How often should we review PCN and EOL notices?
Review every relevant notice immediately. In addition, conduct a regular lifecycle review of active production BOMs—monthly for high-risk programs or quarterly for many stable programs.
Need help reviewing a PCN, PDN, or EOL notice?
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