Why was the LM3900 discontinued ?

[Eric Smith]

Eeyore wrote:

The NTE992 is probably an LM3900.

I wrote:

Sure, but NTE still sells them, while National Semiconductor doesn't.

Michael A. Terrell wrote:

Look at the date codes on the NTE stuff. It's old stock that may be
gone, any day.

Or they might have enough to meet the demand for another century. There's
no way to tell.

I wasn't proposing that anyone should design the NTE992 into a new product.
But if you have something that already uses an LM3900 or NTE992, it doesn't
appear that reengineering it needs to be a crash priority.

Eric

 

[Andre Majorel]

Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

--
André Majorel <URL:http://www.teaser.fr/~amajorel/>
(Counterfeit: abin@bunny.com ubivoq@fleawort.com)
"I drink, I smoke, I gamble, I chase girls--but postal chess is
one vice I don't have." -- Mikhail Tal

 

[MooseFET]

"Andre Majorel" <cheney@halliburton.com> wrote in message
news:slrnfsfdgc.fa5.cheney@atc5.vermine.org...

Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

--
André Majorel <URL:http://www.teaser.fr/~amajorel/
(Counterfeit: abin@bunny.com ubivoq@fleawort.com)
"I drink, I smoke, I gamble, I chase girls--but postal chess is
one vice I don't have." -- Mikhail Tal

Well, my guess is, they may have a better part that can replace it. Why
can't you change your schematic? Are you trying to fix an old board?

For the LM3900's I replaced them with NTE992.





PS. Votre anglais est bien. Félicitation ŕ vous.

 

[mc]

Well, my guess is, they may have a better part that can replace it. Why
can't you change your schematic? Are you trying to fix an old board?

Are there in fact any other quad Norton amplifiers out there? LM3900 is no
ordinary op-amp.

For the LM3900's I replaced them with NTE992.

Isn't the NTE992 merely an LM3900 with different numbers stamped on it and a
higher price? NTE is not a manufacturer -- they're a marketer and
relabeler.

 

[Michael Black]

Andre Majorel (cheney@halliburton.com) writes:

Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

It served really no purpose.

I can remember when it came out, and it was born with a big datasheet
or application note that was loaded with things you could do with it.
But, most of it was novelty, "oh look, here's an LED flasher but you
can do all kinds of other things with it".

It got press early on, but it was rarely used in constructin articles
in the hobby magazines, unless someone used one of those novelty applications.
You had to add a whole IC just to flash an LED? The sorts of things where
it might be really useful, as a very low current LED indicator, you wouldn't
want to devote the space to.

I don't remember it as being particularly available, it must have been but
it never saw the saturation in places that sold to hobbyists that would
indicate it was a popular part.

I've never seen one in any piece of commercial equipment I've taken apart,
which does seem to be an indicator of how little use it saw in commercial
products.

It lasted for decades, but never really served much purpose.

ONe of the odd things is how long a lot of ICs have lasted. In the early
days there was so much turnover, as logic family A was replaced with logic
family B and so on, and as op-amps evolved until they got good. In
retrospect, it's a surprise that a lot of ICs did last so long, because
then the expecation seemed to be that something better would come along
soon to replace anything; after all that had already happened.

A lot of ICs have come and gone, often far more useful or interesting
than the 3909. I can't really fathom why the 3909 lasted so long.

Michael

 

[Michael Black]

Michael Black (et472@FreeNet.Carleton.CA) writes:
Oops, ignore this, I read "3909" (the flasher) instead of "3900" (the
norton amplifier).

Michael

Andre Majorel (cheney@halliburton.com) writes:
Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

It served really no purpose.

I can remember when it came out, and it was born with a big datasheet
or application note that was loaded with things you could do with it.
But, most of it was novelty, "oh look, here's an LED flasher but you
can do all kinds of other things with it".

It got press early on, but it was rarely used in constructin articles
in the hobby magazines, unless someone used one of those novelty applications.
You had to add a whole IC just to flash an LED? The sorts of things where
it might be really useful, as a very low current LED indicator, you wouldn't
want to devote the space to.

I don't remember it as being particularly available, it must have been but
it never saw the saturation in places that sold to hobbyists that would
indicate it was a popular part.

I've never seen one in any piece of commercial equipment I've taken apart,
which does seem to be an indicator of how little use it saw in commercial
products.

It lasted for decades, but never really served much purpose.

ONe of the odd things is how long a lot of ICs have lasted. In the early
days there was so much turnover, as logic family A was replaced with logic
family B and so on, and as op-amps evolved until they got good. In
retrospect, it's a surprise that a lot of ICs did last so long, because
then the expecation seemed to be that something better would come along
soon to replace anything; after all that had already happened.

A lot of ICs have come and gone, often far more useful or interesting
than the 3909. I can't really fathom why the 3909 lasted so long.

Michael

 

[Michael A. Terrell]

mc wrote:

Well, my guess is, they may have a better part that can replace it. Why
can't you change your schematic? Are you trying to fix an old board?

Are there in fact any other quad Norton amplifiers out there? LM3900 is no
ordinary op-amp.

For the LM3900's I replaced them with NTE992.

Isn't the NTE992 merely an LM3900 with different numbers stamped on it and a
higher price? NTE is not a manufacturer -- they're a marketer and
relabeler.

|------||-----|
| DO NOT |
| FEED THE |
| aioe.org |
| TROLL! |
|------||-----|
||
||
||
/|\\|/||||//|||/\???\\//\\\\/|?\/
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[mc]

"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:fq9d73$p8e$1@theodyn.ncf.ca...

Andre Majorel (cheney@halliburton.com) writes:
Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

It served really no purpose.

I can remember when it came out, and it was born with a big datasheet
or application note that was loaded with things you could do with it.
But, most of it was novelty, "oh look, here's an LED flasher but you
can do all kinds of other things with it".
....
A lot of ICs have come and gone, often far more useful or interesting
than the 3909. I can't really fathom why the 3909 lasted so long.

Whoa. LM3909 = low-voltage LED flasher. LM3900 = quad Norton amplifier.
Both are discontinued.

The LM3909 was useful -- it would flash a red LED from a 1.5-volt source, if
I recall correctly. At one point I reverse-engineered it and designed a
discrete-component substitute.

The LM3900 -- well, I couldn't see what it could do that an op-amp couldn't.

 

[Eeyore]

MooseFET wrote:

"Andre Majorel" <cheney@halliburton.com> wrote

Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

Well, my guess is, they may have a better part that can replace it. Why
can't you change your schematic? Are you trying to fix an old board?

For the LM3900's I replaced them with NTE992.

The NTE992 is probably an LM3900.

Do you seriously think they have them made separately ?


Graham

 

[Eric Smith]

Eeyore wrote:

The NTE992 is probably an LM3900.

Sure, but NTE still sells them, while National Semiconductor doesn't.

 

[Michael A. Terrell]

Eric Smith wrote:

Eeyore wrote:
The NTE992 is probably an LM3900.

Sure, but NTE still sells them, while National Semiconductor doesn't.

Look at the date codes on the NTE stuff. It's old stock that may be
gone, any day.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Dave Platt]

The NTE992 is probably an LM3900.

My impression (possibly wrong) is that NTE occasionally buys up the
rights to the original mask/wafer designs of certain parts and has
them fabbed.

Sure, but NTE still sells them, while National Semiconductor doesn't.

It appears that TI is still making the LM3900, in both PDIP and SOIC
formats. DigiKey has only the SOIC in stock. Mouser has both.

Motorola apparently used to make an LM3900-compatible Norton quad
(MC3401) but it looks as if it didn't make the quantum-leap over to On
Semiconductors.

So, the NTE992 might be old-stock NatSemi LM3900s which have been
relabeled, or TI LM3900s which have been relabeled, or parts made by
J-random-fab based on licensed (or non-licensed) designs of one or
another heritage. I don't think there's any way to know for certain,
unless one works for NTE.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Eeyore]

Eric Smith wrote:

Eeyore wrote:
The NTE992 is probably an LM3900.

Sure, but NTE still sells them, while National Semiconductor doesn't.

Until they run out of stock.

Graham

 

[Spehro Pefhany]

On Fri, 29 Feb 2008 16:31:53 -0800, the renowned dplatt@radagast.org
(Dave Platt) wrote:

The NTE992 is probably an LM3900.

My impression (possibly wrong) is that NTE occasionally buys up the
rights to the original mask/wafer designs of certain parts and has
them fabbed.

Sure, but NTE still sells them, while National Semiconductor doesn't.

It appears that TI is still making the LM3900, in both PDIP and SOIC
formats. DigiKey has only the SOIC in stock. Mouser has both.

I see 1500+ of the DIP TI LM3900N in stock at Digikey, but the
LM3900NE4 is non-stock. Offhand I don't see the difference-- they're
both listed as RoHS on the datasheet.

Terrible matching on the current inputs (+/-10%).. makes an LM324 look
like a precision device. I used them in a couple of designs way back--
sort of like BJTs.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Dave Platt]

In article <gsahs3l2l6sk5vgql947qii8r8kqldr2op@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:

Terrible matching on the current inputs (+/-10%).. makes an LM324 look
like a precision device. I used them in a couple of designs way back--
sort of like BJTs.

I've heard them described as being a bit like a super-high-beta BJT.

I ran into an interesting use of them a couple of years ago - in the
audio and squelch stages of a receiver for an amateur-radio repeater.
Best as we could figure out, they were used because they allowed the
design to operate on a single-sided 12-volt power supply (regulated
down to around +8 internally) with a minimum amount of interstage
DC-blocking caps and bias networks being required.

These days, of course, much better parts for this application would be
used, but I don't think there were any good low-voltage, rail-to-rail-
capable op amps in common use back when this receiver design was
finalized.

Sure was puzzling for a while there, though. My cohort-in-crime and I
were tweaking the audio gain and equalization, and changed the
feedback resistor around the amp... and its output pinned at one of
the rails. Led to a puzzled session of headscratching, before the
flashbulb went off and I said "Oh, hell.. LM3900... that's not an op
amp, that's a Norton!"

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[MooseFET]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:47C879EF.CBDC908B@earthlink.net...

mc wrote:

Well, my guess is, they may have a better part that can replace it.
Why
can't you change your schematic? Are you trying to fix an old board?

Are there in fact any other quad Norton amplifiers out there? LM3900 is
no
ordinary op-amp.

For the LM3900's I replaced them with NTE992.

Isn't the NTE992 merely an LM3900 with different numbers stamped on it
and a
higher price? NTE is not a manufacturer -- they're a marketer and
relabeler.


|------||-----|
| DO NOT |
| FEED THE |
| Michael Terribly ill |
| TROLL! |
|------||-----|
||
||
||
/|\\|/||||//|||/\???\\//\\\\/|?\/
--
Service to my deamon? Been there, Done that, and I've got my DD666 to
prove it.
Member of DAV #85.

Michael A. Terribly Ill
Central Florida

Retarded Michael running out of stream? Go get killed in IRAQ NOW stupid
jerk!

 

[MooseFET]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:47C8A383.FA1D4956@earthlink.net...

Eric Smith wrote:

Eeyore wrote:
The NTE992 is probably an LM3900.

Sure, but NTE still sells them, while National Semiconductor doesn't.


Look at the date codes on the NTE stuff. It's old stock that may be
gone, any day.


--
Service to my deamon? Been there, Done that, and I've got my DD666 to
prove it.
Member of DAV #85.

Michael A. Terribly Ill
Central Florida

Quit following my thread dummy Mikhell.

 

[www.ningbo-electric.com]

On Mar 1, 1:27 pm, "MooseFET" <kensm...@rahul.net> wrote:

"Michael A. Terrell" <mike.terr...@earthlink.net> wrote in messagenews:47C8A383.FA1D4956@earthlink.net...





Eric Smith wrote:

Eeyore wrote:
The NTE992 is probably an LM3900.

Sure, but NTE still sells them, while National Semiconductor doesn't.

  Look at the date codes on the NTE stuff.  It's old stock that may be
gone, any day.

--
Service to my deamon? Been there, Done that, and I've got my DD666 to
prove it.
Member of DAV #85.

Michael A. Terribly Ill
Central Florida

Quit following my thread dummy Mikhell.- Hide quoted text -

- Show quoted text -

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[Glenn Gundlach]

On Feb 29, 8:51 am, et...@FreeNet.Carleton.CA (Michael Black) wrote:

Andre Majorel (che...@halliburton.com) writes:
Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

It served really no purpose.

I can remember when it came out, and it was born with a big datasheet
or application note that was loaded with things you could do with it.
But, most of it was novelty, "oh look, here's an LED flasher but you
can do all kinds of other things with it".

It got press early on, but it was rarely used in constructin articles
in the hobby magazines, unless someone used one of those novelty applications.
You had to add a whole IC just to flash an LED?  The sorts of things where
it might be really useful, as a very low current LED indicator, you wouldn't
want to devote the space to.

I don't remember it as being particularly available, it must have been but
it never saw the saturation in places that sold to hobbyists that would
indicate it was a popular part.

I've never seen one in any piece of commercial equipment I've taken apart,
which does seem to be an indicator of how little use it saw in commercial
products.

It lasted for decades, but never really served much purpose.

ONe of the odd things is how long a lot of ICs have lasted.  In the early
days there was so much turnover, as logic family A was replaced with logic
family B and so on, and as op-amps evolved until they got good.  In
retrospect, it's a surprise that a lot of ICs did last so long, because
then the expecation seemed to be that something better would come along
soon to replace anything; after all that had already happened.

A lot of ICs have come and gone, often far more useful or interesting
than the 3909.  I can't really fathom why the 3909 lasted so long.

  Michael

Useless tidbit. Phase Linear used the LM3900 in the model 1000
autocorrelator in the notch filters. It was an interesting alternative
to the Burwen noise reducing box. IIRC Burwen had a sliding corner
lowpass while Phase used 3 broad notch filters / gated by program
material in the respective band. The Phase Linear worked better after
removing the RC4136 (?) opamp and replacing it with a TL075.

GG

 

[RST Engineering (jw)]

I disagree. Its gain-bandwidth product is 3 MHz., triple the gbw of the
venerable LM324, which is why I designed it into (and still use it) in the
RST-523 Aircraft Navigation Receiver, still in production.

Jim

--
"If you think you can, or think you can't, you're right."
--Henry Ford

"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:fq9d73$p8e$1@theodyn.ncf.ca...

Andre Majorel (cheney@halliburton.com) writes:
Anybody knows why National discontinued the LM3900 ? It seems
reasonably popular and, even today, many resellers carry the TI
version. Obsolete fab process ?

It served really no purpose.