Obsolete Parts (EOL): What to Do When Your Component Goes End-of-Life

Obsolete Parts (EOL): What to Do When Your Component Goes End-of-Life

End-of-life (EOL) components are a normal part of electronics manufacturing—but if you handle them badly, they become a disaster: production stops, redesigns get rushed, costs spike, and customers get angry.

This guide explains what EOL really means, how to respond step-by-step, and how to build a sourcing/design process that reduces future EOL pain.

⸻

What “EOL” usually looks like in real life

Most components don’t disappear overnight. Vendors typically go through stages:
• NRND (Not Recommended for New Designs): still available, but vendor signals “don’t build new products on this”
• PCN (Product Change Notification): changes in process, factory, materials, marking, etc.
• LTS / Last Time Buy (LTB): final window to place orders
• EOL / Discontinuation: production ends
• End of Support: no guarantees for documentation, test limits, etc.

Even if the vendor process is “official,” the market often acts earlier:
• lead times increase
• stock becomes inconsistent
• grey market risk rises

⸻

Step-by-step: what to do when a part is going obsolete

Step 1) Confirm the lifecycle status (don’t rely on rumors)

Check:
• manufacturer lifecycle status
• authorized distributor notes
• official PCN/LTB notice if available

Goal:
• find the real end dates and what options exist.

⸻

Step 2) Determine how “critical” the part is

Classify the part:
• Drop-in replaceable (same footprint/pinout): low risk
• Function compatible but footprint change: medium risk
• Unique / no direct substitute (MCU, PMIC, RF): high risk

Also check if it affects:
• safety certifications
• regulatory compliance
• performance specs promised to customers

⸻

Step 3) Identify approved alternatives (don’t chase random “equivalents”)

Best options:
1. Same family upgrade (same footprint, more memory, etc.)
2. Pin-to-pin compatible alternative (same package and pinout)
3. Functionally compatible (needs minor changes)
4. Redesign (worst case)

For each candidate, compare:
• electrical specs and operating range
• package and footprint match
• performance (timing, noise, efficiency, thermal)
• firmware impact (especially MCUs)
• availability and second source options

⸻

Step 4) Make a bridge plan: LTB vs redesign timeline

You usually need a plan with two tracks:

Track A: Keep production running
• place LTB order (if justified)
• allocate stock to production batches
• lock substitutions tightly (counterfeit risk increases during EOL)

Track B: Engineer the replacement
• design change + prototype
• validation testing
• production release

This prevents you from betting everything on a rushed redesign.

⸻

Step 5) Validate the replacement (don’t skip this)

Validation level depends on criticality, but at minimum:
• functional test (all features)
• thermal and load tests
• EMI/ESD sanity checks (especially for power and I/O changes)
• if needed: re-certification impact review

For MCUs/MPUs:
• compiler/toolchain changes
• peripheral behavior differences
• bootloader/OTA compatibility

⸻

Step 6) Update BOM + AVL + documentation so the problem doesn’t return
• add approved alternative(s) to AVL
• update BOM notes (critical specs like MLCC dielectric, MOSFET Rds(on) at gate voltage, inductor Isat)
• update test procedures if needed
• update manufacturing instructions and programming steps

⸻

How to decide if you should place a Last Time Buy (LTB)

LTB can save you, or trap your cash.

LTB makes sense when:
• redesign cost and schedule risk is high
• product is still selling strongly
• storage and shelf-life are manageable
• part is high reliability and traceable (not broker risky)

LTB can be a bad idea when:
• the part is cheap but storage/handling is tricky (MSL moisture parts)
• demand forecast is uncertain
• you can substitute easily
• you’d need to buy from risky sources

⸻

Special cases (where EOL is most painful)

1) MCUs / MPUs

Pain points:
• firmware porting and debugging
• toolchain differences
• memory/peripheral differences
• security/boot changes

Best strategy:
• choose MCU families with multiple footprint-compatible SKUs
• keep a second-source plan early

2) Power ICs (PMIC, charger, regulator)

Pain points:
• stability depends on external parts and layout
• “equivalents” often oscillate or change EMI

Best strategy:
• prefer widely used regulators with multiple vendor options
• follow reference designs and validate thoroughly

3) RF chips/modules

Pain points:
• certification and RF performance
• antenna matching changes

Best strategy:
• prefer certified modules with stable lifecycle
• keep alternates that match regulatory requirements

⸻

EOL prevention (what smart teams do early)

1) Use lifecycle-aware BOM selection
• avoid NRND parts in new designs
• favor parts with multi-vendor ecosystem
• avoid exotic single-source parts unless truly necessary

2) Build second-source options into footprints

Examples:
• choose packages that multiple vendors support
• design footprints that can accept 2–3 compatible parts (when possible)
• keep resistor/cap footprint options for tuning

3) Monitor PCNs and lead-time signals

Even without formal EOL notice, early signs include:
• lead time rising steadily
• distributor stock drying up
• frequent allocation

4) Keep BOM notes tight to prevent “bad substitutes”

Many EOL “fixes” become failure sources because substitutions weren’t controlled.

⸻

Common mistakes (what causes production disasters)
• Waiting until stock is gone before reacting
• Buying LTB from grey market sources with no traceability
• Assuming a “similar part” is drop-in compatible
• Not validating EMI/ESD/thermal after power part changes
• Not updating AVL and documentation (problem repeats next month)

⸻

Quick EOL response checklist

When you get an EOL signal:
• Confirm lifecycle status and dates
• Classify criticality (drop-in vs redesign)
• Identify safe alternatives + availability
• Decide LTB quantity (if needed) + storage plan
• Start redesign/validation in parallel
• Update BOM/AVL and lock critical specs