Author Topic: Part Selection Panic Syndrom. or PS*2  (Read 3967 times)

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Offline calexanian

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Part Selection Panic Syndrom. or PS*2
« on: August 26, 2014, 03:33:46 am »
So I am selecting a buck converter for a new design today and I feel overcome with the feeling of will this part be around in 10 years? Will that fab that makes it be around? Will the company be around? Are apple and LG, GM, and Toyota using buckets of them and once they bring out the new model do they burn the litho? How does the part internally handle over voltage? Under voltage? Pass through? Can I even get a hold of a human who knows?  When did this all become so stressful? Should I just use nothing but jellybean parts from here out?

Is there a counseling group for the modern engineer??

I am starting to think it would just be easier to make tubes again!
Charles Alexanian
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Offline Richard Head

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #1 on: August 26, 2014, 06:01:47 am »
Parts going obsolete is what keeps engineers in jobs! Don't complain, welcome the fact that these parts become impossible to obtain a few years down the line. It helps pay your salary.
Of course none of this applies if you have your own business, which I suspect is the case with you.
However, don't feel alone. I'm in a similar position with choosing a PC board mount DC-DC converter for an isolated RS485 comms module. I've selected a Recom unit and hope to hell that it's still available in 10 years time. I've also found that the minimum order qty of some of these little units is higher than I expected.

Dick
 

Offline dannyf

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #2 on: August 26, 2014, 10:52:28 am »
Quote
I feel overcome with the feeling of will this part be around in 10 years?

It is called life cycle management. A high lucrative but largely ignored business. Essentially you are trying to replicate the functionality of an old design (either at product or device levels) with new designs.

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Offline sacherjj

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #3 on: August 26, 2014, 11:14:33 am »
Wait till you pick a part that is only available if it is put on a board in PRC.  But no one tells you that.  Until you try to source them.  Then you find out why they make your design so cheap, because the government is subsidizing the chip price to make sure to get board assembly business with it, or some such nonsense.     |O
 

Offline T3sl4co1l

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #4 on: August 26, 2014, 02:13:52 pm »
There are product life cycle databases, but you probably have to pay subscription to get into them.

Stay away from Maxim, and stick to the biggest manufacturers: TI, ST, Fairchild, etc.  Select newish looking parts (datasheets will probably be newer than 2010 copyright / last update), with good specs -- avoid unusual package, unusual purpose, or oddly spec'd parts.  If you aren't seeing specs you want, don't use it -- there's probably a bad reason they're hiding it.  Some of the most common pitfalls on regulators are tolerable ESR range, bias current (total supply and under what conditions, input pins, etc.), and compensation (prefer an external comp part if possible).  If you can't avoid an internally compensated part, don't try to make variations on the suggested / app-note circuit, do exactly as they say -- and if it doesn't work, find an applications engineer to yell at!

Tim
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Electronic design, from concept to prototype.
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Offline dannyf

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #5 on: August 26, 2014, 02:45:27 pm »
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because the government is subsidizing the chip price to make sure to get board assembly business with it, or some such nonsense.

That does sound like nonsense.
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Offline calexanian

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #6 on: August 26, 2014, 02:47:50 pm »
Finding an AE who actually knows anything about the specific product requires a mix of Indiana jones and Sherlock Holmes sometimes! "All I want to know is the over voltage characteristics, are there input output clamp diodes and what are the characteristics" requires an act of congress to get answered because its not in the "sales" datasheet!
Charles Alexanian
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Offline nctnico

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #7 on: August 26, 2014, 02:57:57 pm »
However, don't feel alone. I'm in a similar position with choosing a PC board mount DC-DC converter for an isolated RS485 comms module. I've selected a Recom unit and hope to hell that it's still available in 10 years time. I've also found that the minimum order qty of some of these little units
If you are lucky there are many second sources for the DC-DC converter from Murata, XP Power and others.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline NANDBlog

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #8 on: August 26, 2014, 03:14:02 pm »
Big companies make contracts with the subcontractor. "You will supply this unit for x years, and we will buy x million of it each year." There is no obsolescence, as it is worth to run the production line just for them.
If you are buying less than that, than it becomes more difficult. It is actually worth to write to the distributors, and keep a happy relationship with them, to get insider information. You can just ask them for the product life cycle.
And there are the Enhanced product from TI for example. They guarantee some years. Or Fairchild "no obsolance" strategy. I heard, that even maxim changed their behavior in the last few years.
 

Offline DaveW

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #9 on: August 26, 2014, 06:41:15 pm »
Look for automotive grade parts. I'm currently using a Freescale powerpc processor which has an almost guaranteed life of 15 years. Also look at which companies to deal with, some of them turn over products really rapidly, particularly in the memory market. Others, and LT are particularly good at this, seem to regard making something obsolete as a personal failing.
There is software out there which also gives a pretty good idea of risk, we use Silicon Expert at work. I don't know how much the license is but as the cost of a resistor going obsolete is over a million for us, well worth it if you can afford it.
As good practise, try and find companies that supply drop in replacements at the end of life and if not, find parts with multiple sources; and test several parts before committing yourself. It's not unusual to find drop in replacements that turn out not to work in your application
 

Offline mariush

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #10 on: August 26, 2014, 07:09:02 pm »
The "look for automotive grade parts" advice sounds good when price is not an issue.

My "amateur" advice would be to stick to regulators that have common footprints or ones for which you would have a pricier or a "less quality" option, just in case you'd be left hanging with bunch of pcbs made and no parts in stock anywhere. That will give you time to redesign the boards and get them manufactured and so on.

Alternatively, you could design the pcb from the start to have 2 footprints, like some video cards have footprints for smd and through hole capacitors in same area, or three holes for a capacitor (to allow a larger diameter capacitor), or footprint for memory chips in two sizes (maybe soic/bga or tqfp)
 
 

Offline dannyf

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #11 on: August 26, 2014, 07:18:46 pm »
Quote
has an almost guaranteed life of 15 years.

That guarantee is only as good as the company standing behind it.

Do you think the vendor will be around in 15 years? I am not sure even about 5 years. Semicon is a highly volatile industry.
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Offline rob77

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #12 on: August 26, 2014, 07:39:54 pm »
Finding an AE who actually knows anything about the specific product requires a mix of Indiana jones and Sherlock Holmes sometimes! "All I want to know is the over voltage characteristics, are there input output clamp diodes and what are the characteristics" requires an act of congress to get answered because its not in the "sales" datasheet!

that's obvious... it's like that in any of the corporations... the guys supposed to communicate with the outside world are "trained" sales or PR persons and they don't know a flying piece of shit about the tech stuff behind the product... on the other hand the tech guys able to answer your questions are not supposed to talk to the outside world (for a freaking good reason :D)
 

Offline nctnico

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #13 on: August 26, 2014, 08:38:00 pm »
Another option is to get on the list with people they send the 'last time buy' notification to. Then you can decide whether to stock pile the part. Even if a part is obsolete it can be bought from brokers for a long while at a premium price.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline NANDBlog

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Re: Part Selection Panic Syndrom. or PS*2
« Reply #14 on: August 26, 2014, 08:48:03 pm »
Another option is to get on the list with people they send the 'last time buy' notification to. Then you can decide whether to stock pile the part. Even if a part is obsolete it can be bought from brokers for a long while at a premium price.
Tell this to management. "stocking components has a big opportunity cost" and such stupid answers.
I've heard that someone (fairchild maybe?) will actually keep a stock reserved just for you for some years. To keep the bald guys happy.
 


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