OPA211, funny/peculiar graph in datasheet

"Martin Griffith"

** 100% STALE NEWS !!!!!!!!!!!!

Phil Hobbs has done this piece of dumb trivia to death already.

....... Phil

Not in this NG

sci.electronics.design

Your search - opa211 - did not match any documents

Martin

"Martin Griffith" "Phil Allison"

** Yes, right here on October 11 - you dim witted, PITA fool. ** No - your dumb search was 100% defective:

Path: g2news2.google.com!news3.google.com!sn-xt-sjc-04!sn-xt-sjc-01!sn-post-sjc-01!supernews.com!corp.supernews.com!not-for-mail From: Phil Hobbs Newsgroups: sci.electronics.design Subject: "Maybe the universe has always been like this, but I've been too wrapped up in myself to notice..." Date: Thu, 11 Oct 2007 22:08:53 -0400 Organization: Posted via Supernews,

Message-ID: User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.6) Gecko/20070802 SeaMonkey/1.1.4 MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: snipped-for-privacy@supernews.com Lines: 7

To all you op amp gurus: I posted a question and picture in alt.binaries.schematics.electronic about weird THD behaviour in an otherwise very nice op amp, the OPA211.

Cheers,

Phil Hobbs

** So - f*ck off

- you copycat TROLL.

..... Phil

snip s,

I should have known that I should have searched for "Maybe the universe has always been like this..." rather than OPA211.

You too can be a bit of an idiot at times, just occasionally, not really that often, really.......honest

BTW

Not a single reply..... and it should be Mr. Phil Hobbs,

Martin

"Martin Griffith"

( snip copy of Phil Hobbs Oct 11 post on SED )

** A search using "opa211" and specifying SED gets one hit - Phil Hobbs post on Oct 11.

YOU stuffed up - fool.

** Piss off - wanker.

...... Phil

Yeah, I'd like to see what was said in that abse discussion. But whatever it was, it seems clear that dasheet plot can't be relied upon. And I have no idea, Martin, how your mild question set off the bomb. OK, I went and looked; here's the done-to-death thread (I know you've already read this, but others might like to see it, and the abse threads aren't archived):

• Phil Hobbs:

Gents,

As I was helping someone with a TIA design this afternoon, I had occasion to read the data sheet for the OPA211, which appears pretty similar to the LT1028, except that it's a bit more stable and doesn't come in a plastic DIP. It has a curve of THD+noise vs rms output voltage that I found very odd (see attachment).

Everything goes swimmingly until the signal swing on the inputs reaches about 1V rms, and then it hits the wall. This is at a kilohertz, mind, so it isn't an ordinary slew rate issue. It's also _way_ within the CM range, because the plot specifies +- 15V supplies.

Since the problem surfaces at the same input voltage swing makes it look like something in the input stage, but what in the world could be as slow as that?

So what's up with this amp?

• John Larkin:

That graph makes no sense whatever.

If the numbers were different, I'd say that some input back-to-back diodes were conducting... but not at 1 KHz. Also, fig 3 sort of contradicts fig 4. 140 dB is an interesting number, too.

Is it an artifact of the test circuit, fig 41?

If you figure it out, let us know.

• Phil Allison:

** Nothing - Fig 4 is just plain wrong.

Read the text where it states THD < 0.0001% when G = 1 and output level = 3 volts rms.

• Fred Bartoli:

It seems they nicely screwed the DS there.

Not only the G=+1 curve is, ahem, a bit off, but it seems the G=+11 curve could the G=+1 one: the G=11 curve shows 0.15ppm@3V, which is the stated figure for the G=1 case.

They have a documentation feedback link in the page footer and I just sent feedback. Let see what they say...

Your search - opa211 hobbs - did not match any documents.

So you are blaming me that google is not exactly perfect?

Have a good night, bye, (and you use too much white space)

Martin

"Martin Griffith" " Phil Allison "

** Works perfectly when I try it.

YOU are one dumb s*****ad.

** Works perfectly when I try it.

YOU are one dumb s*****ad.

** Fuck off - you BLOODY IDIOT .

....... Phil

So - f*ck off

The f/b link is not for tech stuff, only wrong sort of font stuff

Thank you Win for the copy, none of that showed up on my NG reader or in abse. I'll dig out LT1028 in the morrow

But should I apologise to Phil? This could be a first in SED?

Martin

"Martin Griffith"

** That is *very* hard to swallow.

Such an obscure issue, never mentioned on SED or ABSE prior to Phil Hobbs' posts, somehow gets " independently discovered " by another poster only 7 days later.

Amazing ....

....... Phil

did not return much, please take your meds. It's probably Google redirecting .com to .es domains, and don't take sed so seriously.

You still use too much white space.

Martin

Wow, my very own flame war.... Reminds me of my lottery experience...my mum bought me a lottery ticket once that hit for $100--which makes me the only person I know who's won something in a lottery without ever having bought a ticket in his life. On the other hand, the $100 was nicer. ;)

I suspect that Fred got it right--that the G=1 and G=11 curves are backwards, the labelling is messed up (distortion vs Vin not Vout), and the nonlinearity in each case is from the output banging into the rail. It seems to happen near 10V rms, which is +-14V peak, not bad going for +-15V supplies. I'm still not designing anything based on those curves, though.

Cheers,

Phil Hobbs

Actually, that's sort of interesting...the other Phil Hobbs who comes up is an Australian troll who talks mostly about rugby...must be my Antipodean self. I wonder if there's a Northern Hemisphere Phil Allison? ;)

Cheers,

Phil Hobbs

Sign up to my server, 500$US or 10? a year, it's just not there,90 day retention, AFAIR, just one message, the original, by Mr. P.H, and I could not find it through google.es, so can we please call this sillyness to an end.

And the idea that *only* 2 english speaking people notice a problem in the same datasheet, independantly, and queried it, within a week is not unknown. I should have thought it would be more.

I'm more annoyed about the guys who produced the datasheet in the first place for not spotting it, and geting us into this stupid rut

Martin

Yes, Mr. John Woogate

Martin

My guess is that the typo is the +-15 volt supply specification. If the amp is powered by +-2.5 volts, the narrow common mode range would explain the curves.

Probably, but you are such an easy wind-up.....-)

/me is trying to imagine the reply, even before hitting send

Martin

Yep, Fred is OK, can't figure out if it was a Monday morning or Friday afternoon datasheet

Martin

That's most unfair to John Woodgate, who is never anywhere near as rude as Phil Allison.

-- Bill Sloman, Nijmegen