TCA0372 shortage?...

fredag den 24. juli 2020 kl. 03.48.09 UTC+2 skrev Phil Hobbs:
On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)
Click to expand...

so that bottom should be a darlington and the top Sziklai ?
 
On 7/23/2020 10:15 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.48.09 UTC+2 skrev Phil Hobbs:
On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)


so that bottom should be a darlington and the top Sziklai ?
Click to expand...

Can\'t do a monolithic power PNP AFAIK so the bottom can\'t be a
P-darlington I don\'t think.
 
On 7/23/2020 10:15 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.48.09 UTC+2 skrev Phil Hobbs:
On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)


so that bottom should be a darlington and the top Sziklai ?
Click to expand...

Can\'t do a monolithic power PNP AFAIK so the bottom can\'t be a
P-darlington I don\'t think.
 
fredag den 24. juli 2020 kl. 04.35.02 UTC+2 skrev bitrex:
On 7/23/2020 10:15 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.48.09 UTC+2 skrev Phil Hobbs:
On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)


so that bottom should be a darlington and the top Sziklai ?




Can\'t do a monolithic power PNP AFAIK so the bottom can\'t be a
P-darlington I don\'t think.
Click to expand...

but if the top is a Sziklai it is the equivalent to a PNP
then the bottom should an NPN
 
fredag den 24. juli 2020 kl. 04.35.02 UTC+2 skrev bitrex:
On 7/23/2020 10:15 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.48.09 UTC+2 skrev Phil Hobbs:
On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)


so that bottom should be a darlington and the top Sziklai ?




Can\'t do a monolithic power PNP AFAIK so the bottom can\'t be a
P-darlington I don\'t think.
Click to expand...

but if the top is a Sziklai it is the equivalent to a PNP
then the bottom should an NPN
 
On 7/23/2020 10:15 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.48.09 UTC+2 skrev Phil Hobbs:
On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)


so that bottom should be a darlington and the top Sziklai ?
Click to expand...

Can\'t do a monolithic power PNP AFAIK so the bottom can\'t be a
P-darlington I don\'t think.
 
On Friday, July 24, 2020 at 11:16:42 AM UTC-7, John Larkin wrote:
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
Click to expand...

When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best choice of
part for a DC-coupled application with gain.

But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end routinely though.

but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting


Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application). The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.

For the occasional precision application, wrap a chopamp feedback loop
round it.

Or just calibrate out the offset.
Click to expand...

The chopamp doesn\'t undergo the thermal swings of the output amplifiers, though,
and the input stage of the TCA0372 does.

National even made a input-stage-only chip to solve
that (fairly common) probolem): an LM321 is still available from TI,
but it\'s not the same part at all (just a single of LM324); the old LM321A had
differential outputs, offset trim, and was good for 0.2 uV/C offset drift.
 
On 7/24/2020 7:23 PM, Lasse Langwadt Christensen wrote:
lørdag den 25. juli 2020 kl. 01.05.01 UTC+2 skrev bitrex:
On 7/24/2020 6:16 PM, John Larkin wrote:
On Fri, 24 Jul 2020 17:24:38 -0400, bitrex <user@example.net> wrote:

On 7/24/2020 4:53 PM, John Larkin wrote:
On Fri, 24 Jul 2020 19:37:41 -0400, bitrex <user@example.net> wrote:

On 7/24/2020 2:46 PM, Phil Hobbs wrote:
On 2020-07-24 14:16, John Larkin wrote:
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
On 7/23/2020 7:47 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 01.12.21 UTC+2 skrev bitrex:
On 7/23/2020 7:01 PM, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total
distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2
months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail,
and my
go-to floating ground generator is getting scarce.
razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Looks good but they seem a bit un-confident about the offset voltage
spec...???? it\'s usually somewhere in there

page5: input offset voltage -/+10mV ?


Right. The TCA0372 lists 1mV typ and 15 mV max, when there\'s a wide
spread there I get the impression that the 15mV parts are the real
outlier and don\'t show up much in practice. You could use them for DC
application and expect better and QC out a few boards that got a real
bad one.

When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best
choice of
part for a DC-coupled application with gain.

But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end
routinely though.

but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting


Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application).  The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.

For the occasional precision application, wrap a chopamp feedback loop
round it.

Or just calibrate out the offset.


Sure, if it sits still.  I\'d expect it to walk around a bit, what with
being a power op amp and all. ;)  (Widlar put a paper in the ISSC one
year that purported to prove that monolithic voltage regulators with
on-chip pass transistors were impossible due to thermal feedback.
Everybody believed it because it was Widlar.  Then he came out with the
LM109/309.)

Cheers

Phil Hobbs


Maybe Widlar believed it too for a while, hard to say. I get the
impression a lot of his designs didn\'t immediately work as expected
which is why he carried a sledge hammer I feel the same way sometimes.

I expect they were mostly named after whomever the sexiest secretaries
in the National office was as was the fashion at the time. Aw crap, the
Lauren didn\'t pan out. To the crushing-stump with it.

We met his girlfriend at the bar of the Washington Square Bar and
Grille. I can\'t remember her name.


Seems like the kind of guy who had more than one girl friend. Like Feynman

She was living with him in Puerta Viallarta (sp?) and back visiting
her mom. She was worried about his drinking.

Seems he quit sometime in his late 30s, early 40s maybe? Unfortunately
the effects of 20-25 years of alcoholism don\'t reverse themselves
overnight, if ever. It\'s a sad story in anyone, particularly in creative
types. Some give it up and feel they lost whatever it was that made them
creative, and some never do. The author William Styron wrote about it:

https://en.wikipedia.org/wiki/Darkness_Visible_(memoir)

He had a tablecloth on the kitchen table with IC drawings under it.
She was NOT allowed to look at them.

Alcohol abuse induces paranoia...hard to imagine anyone could design
while drunk but maybe he only worked during sober periods. Or he was
just that good.

I\'m not sure alcoholics are necessarily always \"drunk\"
Click to expand...

Nah. but Widlar doesn\'t seem like the type of guy who did anything
low-key, not the three martini lunch-type. Wasn\'t drunk all the time,
but when he drank I expect he _drank_
 
On 7/24/2020 7:23 PM, Lasse Langwadt Christensen wrote:
lørdag den 25. juli 2020 kl. 01.05.01 UTC+2 skrev bitrex:
On 7/24/2020 6:16 PM, John Larkin wrote:
On Fri, 24 Jul 2020 17:24:38 -0400, bitrex <user@example.net> wrote:

On 7/24/2020 4:53 PM, John Larkin wrote:
On Fri, 24 Jul 2020 19:37:41 -0400, bitrex <user@example.net> wrote:

On 7/24/2020 2:46 PM, Phil Hobbs wrote:
On 2020-07-24 14:16, John Larkin wrote:
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
On 7/23/2020 7:47 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 01.12.21 UTC+2 skrev bitrex:
On 7/23/2020 7:01 PM, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total
distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2
months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail,
and my
go-to floating ground generator is getting scarce.
razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Looks good but they seem a bit un-confident about the offset voltage
spec...???? it\'s usually somewhere in there

page5: input offset voltage -/+10mV ?


Right. The TCA0372 lists 1mV typ and 15 mV max, when there\'s a wide
spread there I get the impression that the 15mV parts are the real
outlier and don\'t show up much in practice. You could use them for DC
application and expect better and QC out a few boards that got a real
bad one.

When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best
choice of
part for a DC-coupled application with gain.

But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end
routinely though.

but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting


Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application).  The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.

For the occasional precision application, wrap a chopamp feedback loop
round it.

Or just calibrate out the offset.


Sure, if it sits still.  I\'d expect it to walk around a bit, what with
being a power op amp and all. ;)  (Widlar put a paper in the ISSC one
year that purported to prove that monolithic voltage regulators with
on-chip pass transistors were impossible due to thermal feedback.
Everybody believed it because it was Widlar.  Then he came out with the
LM109/309.)

Cheers

Phil Hobbs


Maybe Widlar believed it too for a while, hard to say. I get the
impression a lot of his designs didn\'t immediately work as expected
which is why he carried a sledge hammer I feel the same way sometimes.

I expect they were mostly named after whomever the sexiest secretaries
in the National office was as was the fashion at the time. Aw crap, the
Lauren didn\'t pan out. To the crushing-stump with it.

We met his girlfriend at the bar of the Washington Square Bar and
Grille. I can\'t remember her name.


Seems like the kind of guy who had more than one girl friend. Like Feynman

She was living with him in Puerta Viallarta (sp?) and back visiting
her mom. She was worried about his drinking.

Seems he quit sometime in his late 30s, early 40s maybe? Unfortunately
the effects of 20-25 years of alcoholism don\'t reverse themselves
overnight, if ever. It\'s a sad story in anyone, particularly in creative
types. Some give it up and feel they lost whatever it was that made them
creative, and some never do. The author William Styron wrote about it:

https://en.wikipedia.org/wiki/Darkness_Visible_(memoir)

He had a tablecloth on the kitchen table with IC drawings under it.
She was NOT allowed to look at them.

Alcohol abuse induces paranoia...hard to imagine anyone could design
while drunk but maybe he only worked during sober periods. Or he was
just that good.

I\'m not sure alcoholics are necessarily always \"drunk\"
Click to expand...

Nah. but Widlar doesn\'t seem like the type of guy who did anything
low-key, not the three martini lunch-type. Wasn\'t drunk all the time,
but when he drank I expect he _drank_
 
On 2020-07-23 22:13, jlarkin@highlandsniptechnology.com wrote:
On Thu, 23 Jul 2020 16:01:43 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf

Good grief, a drop-in replacement! Almost.

The voltage rating is interesting. 50 volts for 50 milliseconds.

Other strange specs are the single negative supply (0 volts) and the
noise (10 uV).

Good to know about.
Click to expand...

Rochester is showing >120k pieces of the TCA0372 in PDIP, so in a pinch
we could make a reverse DIP breakout board to fit the SO16-wide
footprint. ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 2020-07-23 22:13, jlarkin@highlandsniptechnology.com wrote:
On Thu, 23 Jul 2020 16:01:43 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf

Good grief, a drop-in replacement! Almost.

The voltage rating is interesting. 50 volts for 50 milliseconds.

Other strange specs are the single negative supply (0 volts) and the
noise (10 uV).

Good to know about.
Click to expand...

Rochester is showing >120k pieces of the TCA0372 in PDIP, so in a pinch
we could make a reverse DIP breakout board to fit the SO16-wide
footprint. ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 2020-07-23 22:13, jlarkin@highlandsniptechnology.com wrote:
On Thu, 23 Jul 2020 16:01:43 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf

Good grief, a drop-in replacement! Almost.

The voltage rating is interesting. 50 volts for 50 milliseconds.

Other strange specs are the single negative supply (0 volts) and the
noise (10 uV).

Good to know about.
Click to expand...

Rochester is showing >120k pieces of the TCA0372 in PDIP, so in a pinch
we could make a reverse DIP breakout board to fit the SO16-wide
footprint. ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
fredag den 24. juli 2020 kl. 19.37.38 UTC+2 skrev Phil Hobbs:
On 2020-07-23 22:13, jlarkin@highlandsniptechnology.com wrote:
On Thu, 23 Jul 2020 16:01:43 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf

Good grief, a drop-in replacement! Almost.

The voltage rating is interesting. 50 volts for 50 milliseconds.

Other strange specs are the single negative supply (0 volts) and the
noise (10 uV).

Good to know about.

Rochester is showing >120k pieces of the TCA0372 in PDIP, so in a pinch
we could make a reverse DIP breakout board to fit the SO16-wide
footprint. ;)
Click to expand...

or if you have room for it add both footprints overlapping
 
On Fri, 24 Jul 2020 13:37:30 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 22:13, jlarkin@highlandsniptechnology.com wrote:
On Thu, 23 Jul 2020 16:01:43 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf

Good grief, a drop-in replacement! Almost.

The voltage rating is interesting. 50 volts for 50 milliseconds.

Other strange specs are the single negative supply (0 volts) and the
noise (10 uV).

Good to know about.

Rochester is showing >120k pieces of the TCA0372 in PDIP, so in a pinch
we could make a reverse DIP breakout board to fit the SO16-wide
footprint. ;)

Cheers

Phil Hobbs
Click to expand...

I could also make my own mouse-bite baby board, with an MSOP dual
opamp and some discretes. I really don\'t want to do that. I am using
the wide surface-mount package.

One other possibility is to parallel a LOT of small opamps. I just did
five RRIO amps in parallel, as the bias supply for a lithium niobate
modulator.

I had a beautiful pulser output stage, then the fast PNPs and Avago
phemts both died. My GaN version is beautiful, but I need this opamp.

Actually, the TCA seems to be an active part. We\'ll buy a couple k
more just in case.
 
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
On 7/23/2020 7:47 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 01.12.21 UTC+2 skrev bitrex:
On 7/23/2020 7:01 PM, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Looks good but they seem a bit un-confident about the offset voltage
spec...???? it\'s usually somewhere in there

page5: input offset voltage -/+10mV ?


Right. The TCA0372 lists 1mV typ and 15 mV max, when there\'s a wide
spread there I get the impression that the 15mV parts are the real
outlier and don\'t show up much in practice. You could use them for DC
application and expect better and QC out a few boards that got a real
bad one.

When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best choice of
part for a DC-coupled application with gain.

But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end routinely though.

but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting


Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application). The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.

For the occasional precision application, wrap a chopamp feedback loop
round it.
Click to expand...

Or just calibrate out the offset.
 
On Thu, 23 Jul 2020 21:47:53 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)

Cheers

Phil Hobbs
Click to expand...

That was wrong on rev 9 of the data sheet, issued in 2005!
 
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
On 7/23/2020 7:47 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 01.12.21 UTC+2 skrev bitrex:
On 7/23/2020 7:01 PM, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Looks good but they seem a bit un-confident about the offset voltage
spec...???? it\'s usually somewhere in there

page5: input offset voltage -/+10mV ?


Right. The TCA0372 lists 1mV typ and 15 mV max, when there\'s a wide
spread there I get the impression that the 15mV parts are the real
outlier and don\'t show up much in practice. You could use them for DC
application and expect better and QC out a few boards that got a real
bad one.

When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best choice of
part for a DC-coupled application with gain.

But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end routinely though.

but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting


Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application). The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.

For the occasional precision application, wrap a chopamp feedback loop
round it.
Click to expand...

Or just calibrate out the offset.
 
fredag den 24. juli 2020 kl. 20.21.16 UTC+2 skrev John Larkin:
On Thu, 23 Jul 2020 21:47:53 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)

Cheers

Phil Hobbs

That was wrong on rev 9 of the data sheet, issued in 2005!
Click to expand...

rev 1 1996, http://pdf.datasheetcatalog.com/datasheet/motorola/TCA0372DP1.pdf
 
fredag den 24. juli 2020 kl. 20.21.16 UTC+2 skrev John Larkin:
On Thu, 23 Jul 2020 21:47:53 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 21:34, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 03.22.53 UTC+2 skrev bitrex:
On 7/23/2020 8:55 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.32.21 UTC+2 skrev bitrex:
On 7/23/2020 7:24 PM, Phil Hobbs wrote:
On 2020-07-23 19:01, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce.   razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Awesome, thanks!  It has the same pinout, and for lower supply voltages
it might well be interchangeable.  I\'ll get some and see.

Cheers

Phil Hobbs


Incidentally it\'s cool how the latest revision of the TCA0372 datasheet
was like literally yesterday and it seems no one has noticed the output
stage as drawn doesn\'t make sense...

https://www.onsemi.com/pub/Collateral/TCA0372-D.PDF

I did notice the output on the block diagram made no sense the way
it is drawn, I just assumed some drew an arrow wrong on a transistor
and no one cared :)

it seems it been that way at least back to the Motorola data sheet I
found dated 1996


Even if they drew the upper stage as a regular Darlington it\'s probably
not a very good representation of the output stage, no ballast resistors
in the emitters and three diode drops but they describe \"zero-deadband
crossover distortion.\" Is the slew-rate symmetric?

doesn\'t look symmetric on fig7

three diodes should match an darlington and compound pair no?

The dual-Sziklai totem pole clearly wouldn\'t work as drawn, but it does
suggest the actual performance of the TCA0372--it pulls closer to the
positive rail than your old-school Darlington op amp output. (The lower
limit is much more Darlington-ish.)

Cheers

Phil Hobbs

That was wrong on rev 9 of the data sheet, issued in 2005!
Click to expand...

rev 1 1996, http://pdf.datasheetcatalog.com/datasheet/motorola/TCA0372DP1.pdf
 
On 2020-07-24 14:16, John Larkin wrote:
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
On 7/23/2020 7:47 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 01.12.21 UTC+2 skrev bitrex:
On 7/23/2020 7:01 PM, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!

Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!


for 20V wouldn\'t this be an alternative?

https://www.st.com/resource/en/datasheet/l2720w.pdf


Looks good but they seem a bit un-confident about the offset voltage
spec...???? it\'s usually somewhere in there

page5: input offset voltage -/+10mV ?


Right. The TCA0372 lists 1mV typ and 15 mV max, when there\'s a wide
spread there I get the impression that the 15mV parts are the real
outlier and don\'t show up much in practice. You could use them for DC
application and expect better and QC out a few boards that got a real
bad one.

When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best choice of
part for a DC-coupled application with gain.

But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end routinely though.

but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting


Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application). The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.

For the occasional precision application, wrap a chopamp feedback loop
round it.

Or just calibrate out the offset.
Click to expand...

Sure, if it sits still. I\'d expect it to walk around a bit, what with
being a power op amp and all. ;) (Widlar put a paper in the ISSC one
year that purported to prove that monolithic voltage regulators with
on-chip pass transistors were impossible due to thermal feedback.
Everybody believed it because it was Widlar. Then he came out with the
LM109/309.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
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