Guides / Replacing obsolete parts · Data from 21 October 2026

How to replace an obsolete or out-of-stock part

Sooner or later a part in your BOM goes out of stock or gets an end-of-life notice. The fix depends on what kind of part it is: a resistor can be swapped in minutes, a radio module cannot. Here are four real cases from October 2026 and how each one was handled.

First, what the status means

Out of stock: the part is still made, but the distributor has none today. It may be back next week or in six months.
Not recommended for new designs (NRND): still made and sold, but the manufacturer has a successor and may end production. Fine for an existing product, a risk for a new one.
Obsolete or end of life: no longer made. Distributors sell what is left.

Case 1: an obsolete part that is still easy to buy

The ICS-43434 I2S microphone from TDK InvenSense is marked obsolete. On 21 October 2026 DigiKey still had 79,004 on cut tape at $2.3172 each for 100, and JLCPCB had 2,268. Mouser had none.

What to do: obsolete does not mean unavailable today. For a one-off or a small batch, buying it is fine. For a product, plan the replacement now. In the OpenPocket recorder the design moved from a breakout board with this microphone to Adafruit's SPH0645 breakout, which fits the same wiring.

Case 2: an NRND module where search does not help

The ESP32-C3-MINI-1-N4 Wi-Fi/BLE module is marked not recommended for new designs. DigiKey had 2,711 at $2.4502; Mouser had none.

A parametric search for replacements is the wrong tool here. Our own find_alternatives has no comparison rules for RF modules, so it returned unverified "similar" parts from the same category: a 2.4 GHz transmitter, a cellular module and a 433 MHz transceiver. None of them would work, and the tool says so.

What to do: for modules and microcontrollers, go to the manufacturer. Espressif publishes which module replaces which, and a successor in the same family usually keeps the footprint and most of the firmware. Check the product change notice before you redesign anything.

Case 3: an out-of-stock resistor

The RC0201FR-077K5L (YAGEO, 7.5 kΩ, 0201, 1%) was out of stock at both Mouser and DigiKey. A search for compatible parts in the same 0201 package found four, each checked on resistance, tolerance and power:

RC0201DR-077K5L (YAGEO, ±0.5%): $0.0047, 8,158 in stock at JLCPCB
RT0201BRD077K5L (YAGEO thin film, ±0.1%): $0.0401, 7,418 in stock
0201WMF7501TEE (UNI-ROYAL, ±1%): $0.0016, 6,786 in stock
GR0201F7K5TAG00 (GiantOhm, ±1%): $0.0008, 1,510 in stock

What to do: passives are the easy case. Match the value, keep the package, take the same or tighter tolerance and the same or higher power and voltage rating. If JLCPCB assembles the board, a no-fee part in a bigger package may be cheaper still; see the JLCPCB basic parts list.

Case 4: an active part out of stock in one place

The LMR51635YDDCR buck converter from TI was listed at both DigiKey and Mouser with zero stock on 19 October 2026. JLCPCB had 2,760.

What to do: before redesigning, check every distributor. An IC that is gone in one place is often in stock in another, at a similar price. If it is gone everywhere, look for a pin-compatible part from the same manufacturer first, then compare the datasheet line by line: pinout, input range, current, switching frequency and the external parts it needs.

A checklist that works for any part

Check the lifecycle status and the stock at every distributor you can buy from, for the quantity you need.
Look at the stock history. A part that went out of stock several times in the last few months will do it again.
Keep the footprint. A replacement in the same package means no PCB change.
Compare the specs that matter for that part type, not just the headline value.
Compare the pinout. Same package does not mean same pins, especially for ICs.
Update the BOM with the new part number and keep the reason next to it.

Next Everything does steps 1 to 4 from an AI assistant: get_part shows the lifecycle and a 120-day stock history, and find_alternatives returns same-package replacements with the comparison for each. Pins are not compared yet, so step 5 is still yours.

About the data

The numbers in this article come from Next Everything, an MCP server we build that lets AI assistants such as Claude, Cursor and Codex check a BOM against the JLCPCB/LCSC catalog and live Mouser and DigiKey prices. If you want to run the same check on your own BOM, the setup guides show how to connect it.

Next Everything is not affiliated with Mouser, DigiKey, JLCPCB or LCSC. Prices are list prices in USD at the time stated and change daily.