op amp inputs

for example, LM324
http://www.st.com/stonline/books/pdf/docs/4797.pdf
the data sheet states a differential voltage of as much as 32 volts is
permissible.
But in the diagram it looks like at about 15 or 20 volts input
differential the b/e junctions on one of the inputs would go into
reverse conduction.
Do I misunderstand or do they use protection circuitry not shown in
the diagram.

 

Read all the info. You'll see note 1 "Neither of the input voltages
must exceed the magnitude of Vcc+ and Vcc-"

Are you referring to the diodes from both inputs to the power supply
rails? Those would certainly be the 'limiting' factor.

GG

 

I think the PNP input transistors have been doped to produce
base emitter reverse break down voltage exceeding the
maximum supply voltage rating. This compromise reduces the
performance possible with these transistors, but makes using
this opamp with open loop inputs, very easy.

 

Jamie wrote:
..

....Including all sorts of DC and low frequency (not audio)
signal applications, and audio if you can arrange the load
to keep only one side of the output totem pole conducting
throughout the waveform (or if distortion is not very
important, like alarm buzzers or telephone quality voice).

 

And also, if I remember correctly, the LM324 is one of those op-amps
that has a discontinued output. meaning, when the follower outputs
cross the zero path or near it, there is no minimum bias for both rails
being applied to maintain constant current. In a way, this is good in
equipment that wants to save on energy when it's used in things like
OSC's, voltage comparator etc..

 

You mean 'do the input transistors' b-e junctions go into avalanche breakdown' ?

It's always puzzled me too.

You'd probably need to ask an analog IC designer.

Graham

 

More use of weird and wacky nomenclature from Jamie the Clueless.

Did you mean 'the output stage has zero quiescent current' ? In which case I
believe the answer is yes, or 'close to zero'.

I fail to see why you introduced this, since it has nothing to do with the OP's
question.

Graham

 

Ok idiot, Most people that come here and read are entry level or minor
techs, they don't need to see the book thrown at them. What a jerk you
are.
Let me tell you something, I put my son through Electronic Engineering
College.
My son is a very intelligent kid how ever, having instructors
throwing the lingo at him like that when he is really trying to get a
grasp on
what the instructor is trying to convey made it hard. Not just him but
many other of his class mates.

I helped him a lot in conveying the terminology into terms that he
could understand. He then past that over to his class mates which also
helped. I can say that he graduated with high oners (4.5) average.

He got into the habit of taking down lots of notes in this class and
I had to do a sit down with him at least 2 times a week.

That's not bad for a kid that is dyslexic.

So, you can use all the text book terms you want. I know what they are
and choose not to use them here. I know those that are interested
to learn about the subject are also eager to engage, its a pity idiots
like you have to spoil it with your commentary.

There are a few here I have a lot of respect for. That is only because
they do know what they're doing and I noticed they only speak up towards
people like you and help others that are trying to understand in the
various ways of examples they offer to convey the answer. They normally
don't leave with an insulting remark to alienate them.

Sure doesn't sound like you does it ?

 

Yet that is exactly what YOU do.

My answers are normally short and succinct and keep to topic, whereas yours are
rambling, off-topic and full of errors including 'using the wrong words'.

Graham

 

Yes, I remember years ago when I run into a problem with a 324
going into oscillation in a particular circuit we were adapting
from another op-amp type. the oscillation was only aprox .2 Pk-PK volts.
using a feed back cap stopped that how ever, it also added to the
miller effect problems. I think what we ended up doing was offsetting
the + input via a pot and placing a (-) load on the output to force
the OP-amp to correct. We only needed a 0..5 volt output on this OP.

 

He's been sinking into snarling-mad-dog, insult everybody, Roy L Fuchs
mode for some time now. Just another sad insult-bot usenut.

John

 

How big of you !

I learnt a huge amount of electronic knowledge even before I went to Uni/college. Nor
did I have anyone to 'put me through' either.

That's because many university lecturers are clueless idiots who are totally divorced
from the real world and real world ways of doing things. I had the same problem at
UCL.

There is however no excuse not to know what 'quiesent current' means since it's a
very widely used term to describe a very important issue. Instead you rambled on
about ......

" a discontinued output. meaning, when the follower outputs cross the zero path or
near it, there is no minimum bias for both rails
being applied to maintain constant current. In a way, this is good in equipment that
wants to save on energy when it's used in things like OSC's, voltage comparator etc..
"

Which is a perfect example of the very thing you were criticising. It also makes no
damn sense.

Graham

 

Miller effect in an op-amp circuit ?

Once again, you're using technical terms in an inapproriate way.

Graham

 

I suggest you read my posts HERE !

I only snarl at ineducable American idiots.

Jamie IS a clueless twat and posts idiotic nonsense that never answers the OP's
questions.

Graham

 

That makes sense.

 

Typical trash.

 

Hit the books trash.

 

go wipe your ass, you stink.
btw, clean your keyboard afterwards. it's most likely full of brown
residue and drool.

 

Why are you writing nasty invective to someone who is trying to help?
You make it extremely difficult to believe your claims.

 

Ha, sorry, but you must be new.. stick around for a bit.
you'll get the picture. When he's doing any replies to
things I write, it's only to help him self.

Maybe you haven't been here long enough.

Have a good day.