Yet Another OPAMP Query - LF353

[Watson A.Name - \Watt Sun, the Dark Remover\]

The National LF353 datasheet implies that the LF353 will sub for both
the LM1558 and LM358. The LM358 and its quad version, the LM324, are
both capable of having their inputs at ground or the negative rail.

I look at the National schematic of the LF353 and it shows the inputs
are gates of a differential pair of P-channel depletion mode JFETs. If
both inputs were tied to the positive supply, they would be okay, but I
don't know if they could both be grounded. Does anyone have a
datasheeet or reference that can confirm this or not? Thanks.

Yeah, I googled for datasheets and ended up on semiconductors.com AKA
Philips. I ended up in an endless loop of choosing English language,
discretes, documents, etc. over and over again. Sucks. Really sucks.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Fred Bartoli]

The National LF353 datasheet implies that the LF353 will sub for both
the LM1558 and LM358. The LM358 and its quad version, the LM324, are
both capable of having their inputs at ground or the negative rail.

I look at the National schematic of the LF353 and it shows the inputs
are gates of a differential pair of P-channel depletion mode JFETs. If
both inputs were tied to the positive supply, they would be okay, but I
don't know if they could both be grounded. Does anyone have a
datasheeet or reference that can confirm this or not? Thanks.

Yeah, I googled for datasheets and ended up on semiconductors.com AKA
Philips. I ended up in an endless loop of choosing English language,
discretes, documents, etc. over and over again. Sucks. Really sucks.

Why don't you look at the obvious place ?

http://www.national.com/pf/LF/LF353.html#Datasheet

BTW, P channel JFETs input opamps obvioulsy can't operate at negative rail
input CM voltage because of the required positive VGS. Here the darlington
input stage of the 358 leave enough room for the current mirror and input
stage transistors to work at just VBC = 0V.

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

"Fred Bartoli"

"Watson A.Name - "Watt Sun, the Dark Remover"" <[email protected]> a
écrit dans le message de
Why don't you look at the obvious place ?

http://www.national.com/pf/LF/LF353.html#Datasheet

That's where I said that I got the information from in my original post,
above.

BTW, P channel JFETs input opamps obvioulsy can't operate at negative rail
input CM voltage because of the required positive VGS. Here the darlington
input stage of the 358 leave enough room for the current mirror and input
stage transistors to work at just VBC = 0V.

The problem I see is that this 'gotcha' is not apparent to most people,
and it needs to be brought to their attention.

I'm still trying to figure out what possesses people to add an extra
space between the end of a sentence and the question mark, !, etc.
That's not in any reference that I know of.

 

[Fred Bartoli]

That's where I said that I got the information from in my original post,
above.

Ah... sorry. I read a bit too fast.

The problem I see is that this 'gotcha' is not apparent to most people,
and it needs to be brought to their attention.

This is written in the datasheet p2 : VCM = +/-11V min, +15/-12 typical.

The pb is more in the somewhat misleading introdutory paragraph.

I'm still trying to figure out what possesses people to add an extra
space between the end of a sentence and the question mark, !, etc.
That's not in any reference that I know of.

That is the standard rule in French.
Insert a space before question and exclamation marks, colon and semicolon,
but not before suspension points, comma and period.

I find this is where it's the more difficult to adapt to english (or
whatever foreign language), because punctuation subtleties easily escape the
attention of the non native writer/reader that I am.

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

"Fred Bartoli"

"Watson A.Name - "Watt Sun, the Dark Remover"" <[email protected]> a
écrit dans le message de
Ah... sorry. I read a bit too fast.


This is written in the datasheet p2 : VCM = +/-11V min, +15/-12 typical.

The pb is more in the somewhat misleading introdutory paragraph.


That is the standard rule in French.
Insert a space before question and exclamation marks, colon and semicolon,
but not before suspension points, comma and period.

I find this is where it's the more difficult to adapt to english (or
whatever foreign language), because punctuation subtleties easily escape the
attention of the non native writer/reader that I am.

That's new to me, I was in Germany for almost a year and a half when I
was in the army, and I don't remember ever seeing that in German text.
In any case, IMNSHO it's becoming a bad habit among the U.S.
semi-literates who post in Usenet and other venues, along with the "Tks
4 IMing me" abbreviations that those suppsedly '3l33t doods' are trying
to force down the throats of the general reader. Thanks for telling us
about this, I had no idea that it was a standard.

Now the next problem is to find a FET input opamp substitute for the 358
and 324 that has the same capability of operating with both inputs at
the negative rail. I checked the TL082 and it's the same as the LF353.
Any suggestions? Thanks.

 

[Fred Bartoli]

That's new to me, I was in Germany for almost a year and a half when I
was in the army, and I don't remember ever seeing that in German text.
In any case, IMNSHO it's becoming a bad habit among the U.S.
semi-literates who post in Usenet and other venues, along with the "Tks
4 IMing me" abbreviations that those suppsedly '3l33t doods' are trying
to force down the throats of the general reader. Thanks for telling us
about this, I had no idea that it was a standard.

That's only for french language and I've absolutly no clue about what it is
for german or other languages.
IIRC, JT's wife is german. Maybe he could tell you ? Oops, maybe he could
tell you?

Now the next problem is to find a FET input opamp substitute for the 358
and 324 that has the same capability of operating with both inputs at
the negative rail. I checked the TL082 and it's the same as the LF353.
Any suggestions? Thanks.

You won't have any chance with PJfets opamps.
Look for NJfets ones, like AD822 for ex. As you don't tell any info I
choosed one that almost match the TL082 you mentionned.
If you want ultra low Ibias look for a P channel MOSFET opamp, since those
are enhancement and not depletion mode and thus have negative VGS instead of
positive. National and AD have some, and probably other mnfr.

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

"Fred Bartoli"

"Watson A.Name - "Watt Sun, the Dark Remover"" <[email protected]> a
écrit dans le message de
That's only for french language and I've absolutly no clue about what it is
for german or other languages.
IIRC, JT's wife is german. Maybe he could tell you ? Oops, maybe he could
tell you?


You won't have any chance with PJfets opamps.
Look for NJfets ones, like AD822 for ex. As you don't tell any info I
choosed one that almost match the TL082 you mentionned.

Hmm, yes, I can tell you're not a native speaker. Blame those bloody
Englishmen across the channel for the anomalies in the language, such as
choosing chosen instead of choosed, which does make more sense and
conforms to convention.

If you want ultra low Ibias look for a P channel MOSFET opamp, since those
are enhancement and not depletion mode and thus have negative VGS instead of
positive. National and AD have some, and probably other mnfr.

Another thread I just read, about an audio switch schematic in ABSE, one
poster complained that it uses the LM324 which has less than good audio
performance.

So what I'm looking for is a better jellybean dual opamp that's not hard
to get, and doesn't cost a lot. And will operate with inputs at the
negative rail. Some common filter configurations need decent hi freq
performance just so the filter will do the job with high freqs. Thanks.

 

[clicliclic]

Another thread I just read, about an audio switch schematic in ABSE, one
poster complained that it uses the LM324 which has less than good audio
performance.

So what I'm looking for is a better jellybean dual opamp that's not hard
to get, and doesn't cost a lot. And will operate with inputs at the
negative rail. Some common filter configurations need decent hi freq
performance just so the filter will do the job with high freqs. Thanks.

Finally we are getting at the heart of the matter. The problem with
the LM358 and LM324 is not in the input stage (so you don't have to
limit yourself to FETs), it's in the output stage: a look at the
interconnected bases of the pull-up and pull-down devices in the
datasheet schematic will give you an idea of the cross-over distortion
to be expected.

The MC3403 (about USD 0.20) is very similar to the LM324 but at least
it has a (not very impressive) distortion spec. In fact the output
stage looks better. I don't know if there is dual version.

How about the LMV272 (3MHz, 2.3V/us, 0.3V/uV)? This is a CMOS OpAmp
for 2.7V to 16V supply and featuring a rail-to-rail output stage, the
inputs reach down to the negative supply. I don't know if you find
this one easy to get (about USD 0.50).

Martin.

 

[clicliclic]

Another thread I just read, about an audio switch schematic in ABSE, one
poster complained that it uses the LM324 which has less than good audio
performance.

So what I'm looking for is a better jellybean dual opamp that's not hard
to get, and doesn't cost a lot. And will operate with inputs at the
negative rail. Some common filter configurations need decent hi freq
performance just so the filter will do the job with high freqs. Thanks.

.... oops: The OpAmp I had in mind in my previous post was the TLV272
(Texas Instruments).

Martin.

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

"Watson A.Name - \"Watt Sun, the Dark Remover\""

Finally we are getting at the heart of the matter. The problem with
the LM358 and LM324 is not in the input stage (so you don't have to
limit yourself to FETs), it's in the output stage: a look at the
interconnected bases of the pull-up and pull-down devices in the
datasheet schematic will give you an idea of the cross-over distortion
to be expected.

The MC3403 (about USD 0.20) is very similar to the LM324 but at least
it has a (not very impressive) distortion spec. In fact the output
stage looks better. I don't know if there is dual version.

How about the LMV272 (3MHz, 2.3V/us, 0.3V/uV)? This is a CMOS OpAmp
for 2.7V to 16V supply and featuring a rail-to-rail output stage, the
inputs reach down to the negative supply. I don't know if you find
this one easy to get (about USD 0.50).

Google couldn't find anything on the LMV272, but said you mean LMC272?
and gave me the datasheets for the Nat'l part. But from their website,
it looks like it might be an obsolete part? or??

 

[datasheet]

http://www.datasheet4u.com


http://de.datasheet4u.com

:lol: [/url]

 

[[email protected]]

http://www.datasheetarchive.com too

 

[James Morrison]

http://www.datasheetarchive.com too

www.google.com too.

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

www.google.com too.

Using the following format:
<part number> datasheet

Example:
2N3055 datasheet

 

[Michael A. Terrell]

Using the following format:
<part number> datasheet

Example:
2N3055 datasheet

PDF 2N3055 datasheet would help filter out some garbage if you get
too many hits.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida

 

[Franc Zabkar]

PDF 2N3055 datasheet would help filter out some garbage if you get
too many hits.

I use "2N3055 filetypedf".


- Franc Zabkar