How can I evaluate or speculate on a part's production lifetime for long term part sourcing?

Question

Suppose I have an idea for a product, where if it were successful, would be in production for 5-10 years. How can I make decisions on what parts to use now such that they will still be available to order in the future?

I'm not old enough to know, but I have heard from those that have been around long enough that some parts, such as some based on the Motorola 68HC11, have been able to stand the test of time and are still available today in pin-compatible and (roughly) code compatible packages and variations.

ARM has looked extremely attractive to me lately, a lot of Cortex-M's seem to fit perfectly for an idea that I have but what guarantees do I have that a pin-compatible variation of a particular micro-controller will still be around in 5 years? Or 10 years? How do I even begin to evaluate this? What are the key factors and does anyone keep data on a chip's production lifetime?

Answer 1

There are no guarantees, not even for the 68HC11. Ask your supplier what the policy on obsoleting parts is. Usually they send a notification with a last buy date. You'll have to buy sufficient parts to cover the remaining production years, or at least until you have a redesign ready. Depending on your relationship with your manufacturer (read: how many parts you purchase per year) you may get an early warning.

On one occasion, for a custom IC the manufacturer didn't discontinue the part, but raised the price to such ridiculous levels that we decided ourselves to stop production. This was an IC produced with an older process which didn't have much production anymore.

Like Olin says, look out for second sources. If your supplier discontinues a part you may still find it at other manufacturers. But scrutinize datasheets. Sometimes second sources aren't exact copies, and the details may need a engineering changes in your design. If you're lucky this is just a resistor value, if you're out of luck this could be an extra resistor.
Also, changing manufacturers may also imply a different price, and a (much) higher price for the part may be a reason for a redesign, especially if you're running large production.

edit
Mike mentions the Flash memory market as notorious for its volatile availability. This is probably due to continuous advances in the field, especially in memory size.
Also expect short life times for emerging technologies, like OLED. I've had OLED modules becoming obsolete before we finished our design!

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Further reading
NXP sample product discontinuation notice

Answer 2

As Steven said, there are no guarantees, but there are things you can look at to make some judgements.

First, how mainstream and multi-sourced is the part? Something like the 74xxx series logic chips have been around since silicon was discovered, are produced by various vendors, and will probably be around in some for at the end of time along with cockroaches and smelly socks.

However, many parts, although popular today, are single sourced. Microcontrollers are like this since every vendor has their own sets of wrinkles to add. All you can do is look at the company's history. Individual microcontrollers due to the nature of their technology go obsolete quickly. See how the company has dealt with that over the years. Some are significantly better than others. You can still today buy the long obsolete Microchip PIC 16C54 or 16F84. There are newer parts that cost less, do more, and fit in the same footprint, but Microchip understands the nature of long term products and these are still available.

Also keep in mind that ARM is just a architecture, not a particular part. There will likely be ARM-based products for a while yet to come, but that is of little relevance to your design. You need the specific individual part you are using from that vendor to still be available in 10 years. That said, if the part does go obsolete in 5 years there will more likely be a reasonably compatible replacement if the original part was from a major family.

So the short answer is you have to do your homework and study up on how well the vendor has dealt with this issue over the last 20 years. If the part you are considering is from a new vendor that doesn't have at least a 15 year history, then pick one that does if you're worried about longevity. In the stock market they say past performance is not guarantee of the future success. That's true, but it means more in the semiconductor business where each company has evolved a sort of corporate philosophy.

Answer 3

(in some sort of order of effectiveness)

• Don't design to the edges of the specs of your part. If you design for your NPN transistor to have a Beta of >100 and a Icmax of 100 mA you will be able to switch to a different part very easily. You might even explicitly design for more than 1 type of part.
• Look for components that are manufacturered by different companies (second sourcing). I think I can make a safe bet that the 555, 7805, ULN2803 end even the 741 will still be available 10 years from now. But be aware of subtle differences of the 'same' part from different sources.
• Look at the track record of a company. For instance, Microchip's PIC chips are not the nicest CPU designs, but the company has a great record for keeping old parts available. Motorola, Atmel and Dallas have a very different reputation.
• Make your design modular, so when one component needs to be changed you don't have to re-design the total product. For software you can do a lot to make it more easily portable over let's say 32-bit microcontrollers (ARM, cortex, PIC32, AVR32, ...)
• For a cheap component that is vulnerable to becoming unavailable you could consider stocking it yourself.

Note that you won't get something for nothing: these measures will cost you, so you might need to quantify your need for long term availability, and weight it against the cost of (partial) re-design. (IME re-design is not that costly, re-testing, re-rectification etc. are the real costs)

Answer 4

Talk to the sales reps of the different companies and ask about their track record for part lifecycles.

Some companies have a nasty history of discontinuing parts, or particular package styles. Others -- like TI and Microchip -- are pretty stellar in having long life cycles. You can still buy PIC16F84 microcontrollers -- and I can remember buying them in college in 1995 (16 years ago!) when they were fairly new.

Answer 5

Also consider how popular a part is, and what markets it is used in. Manufacturers respond to demand, so if demand dries up, so will supply. For example, a processor used in a smartphone could be obsolete next year, as sales of that smartphone end. However a processor used in a popular range of industrial controllers could be around for decades, as that market is slow to change

Answer 6

Take a look at industrial parts ranges.

In the industrial parts range, the parts tend to hang around for a relatively long time. They cost more, and are generally a couple of generation behind on technology, but they are going to be available for a while.