Advertized Parameters, Offset V, ARGH!

Jul 28, 2011 13 Replies

So I go shopping for amps with moderately low input offset voltages. I'm being cheap, so I'm taking my Digi-Key output and sorting by price.



WTF!!! The LM358 has a typical offset of 1mV, with maximum of 3mV. That's fair. But the LM833, which made me all enthusiastic with a typical offset of 150uV has the SAME MAXIMUM OFFSET as the LM358.



I don't care about _typical_!! Gimme WORST CASE for crying out loud:



"Tim, why do 5% of your boards fail the current accuracy test" "Well, the accuracy figure I quoted is ONLY A TYPICAL VALUE! HAHAHAHAHAHA!"



Where will I find my return business?



BTW: I'm looking for a cheap-ish, jelly-bean-ish op amp whose WORST CASE offset voltage is 1mV or less.


www.wescottdesign.com

Welcome to the world of sales and marketing :-)

Ye olde OP07 has become cheap, around 30c in qties:

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You'd have to get confirmation that the 250uV max is valid without external trim (it should). And without Mars and Jupiter to have to be in a certain constellation.

MCP6061 is pretty good as well, comes in 2- and 4-pack as well. But you haven't said what voltage, speed, and so on.

Regards, Joerg http://www.analogconsultants.com/

I haven't, because I was mostly just whining. I had thought of making a separate post with The Whole Question, and I think I'll do so now!

www.wescottdesign.com

Digikey seems to have dropped a notch. Was looking for converters today and the list does like 180mA, 1A, 250mA, 290mA ... ARRRGH&%#!!

Maybe they lowered the threshold for the data entry folks?

Regards, Joerg http://www.analogconsultants.com/

Arrow does the same. I told our rep that I wouldn't use their site until they got that fixed.

Nope. Programmers.

snipped-for-privacy@att.bizzzzzzzzzzzz expounded in news: snipped-for-privacy@4ax.com:

..

It looks like an alpha based sort:

180ma 1A 250mA 290mA ...

So the first char, then the 2nd char etc.

The problem is likely rooted in mgmt though- the programmer rarely is granted time enough to get things done "right".

Warren.

Yup. It's evolution in action. If you go and fire your programmers who take the extra day to do it right because they "take too long" then the programmers that survive will be ones that do things like that.

Then, when your competitors start hiring those damned slow-tops and engineers buy from them instead of you -- you die, and Darwin wins.

www.wescottdesign.com

Could it be an outsource-problem?

I had a serious chat with the guys from our utility yesterday (PG&E). They had quietly dropped the baseline on us which caused the bill to jump up. After I debunked half a dozen excuses via the phone I leveled it, pointed the supervisor's supervisor onto their web site. Had the old baselines. "Yeah, but, we can't update it the millisecond things change" ... "You told me the change happened over a month ago" ... "Ahm, well, ahem, we'll call you back on that". Today someone called back and was very apologetic. They had obvisouly also hand-corrected the web site.

And no, while a supermarket will and has to honor the posted price, they didn't.

Guess their programmers don't really understand how databases work, or maybe they outsourced it.

Regards, Joerg http://www.analogconsultants.com/

Outsourcing is lowering the threshold.

snipped-for-privacy@att.bizzzzzzzzzzzz expounded in news: snipped-for-privacy@4ax.com:

If you ever get radiation treatment, you'll be glad those "dumb programmers" took the time to get it right.

Warren

snipped-for-privacy@att.bizzzzzzzzzzzz expounded in news: snipped-for-privacy@4ax.com:

Well, if they didn't get it right, then they were the ones that thought they were so smart in getting the job done quickly- because according to your remark, the ones taking longer to get it right must be "dumb".

Warren

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