LM358 RRO

Mar 3, 2020

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

George Herold · Mar 3, 2020

On Tuesday, March 3, 2020 at 12:08:52 PM UTC-5, jla...@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

I don't know this opamp. Like the LM324 we've been discussing?

Does rail to rail out mean ~ 1 saturated transistor (Vce) drop?

I'm afraid I don't 'get' the circuit. You're loading the opamp
with ~1.5 mA current source. This keeps the pnp output transistor
to the neg power rail always on. Is the power opamp a buffer?
Isn't the rail to rail performance limited by the power opamp?

George H.

--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

John Larkin · Mar 3, 2020

On Tue, 3 Mar 2020 09:40:59 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Tuesday, March 3, 2020 at 12:08:52 PM UTC-5, jla...@highlandsniptechnology.com wrote:
I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

I don't know this opamp. Like the LM324 we've been discussing?

It's basically a dual version of the 324.

Does rail to rail out mean ~ 1 saturated transistor (Vce) drop?

I'd like it to go within millivolts of the positive rail. "RRO"
usually means all the way.

I'm afraid I don't 'get' the circuit. You're loading the opamp
with ~1.5 mA current source. This keeps the pnp output transistor
to the neg power rail always on. Is the power opamp a buffer?
Isn't the rail to rail performance limited by the power opamp?

The power amp is a TCA0372 as a follower, which will pull up to within
1 volt of my +24 positive rail. I just don't want to give up any more
swing in the driver amp.

Since my load on the 358 is an opamp, I guess the depletion fet could
be replaced with a pullup resistor. The opposite of what people
usually do to an LM324.

I can't add gain to the big amp, which would solve the swing problem,
because it messes up my clamp thing.

TCA0372 is amazing. A dual 1-amp opamp for 47 cents. The LM358 costs
10 cents.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

bitrex · Mar 3, 2020

On 3/3/20 12:40 PM, George Herold wrote:

On Tuesday, March 3, 2020 at 12:08:52 PM UTC-5, jla...@highlandsniptechnology.com wrote:
I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

I don't know this opamp. Like the LM324 we've been discussing?

The LM358 specs look identical to an amp in a LM324N. The LM358A has
somewhat better Voffset and input bias current tolerances.

Does rail to rail out mean ~ 1 saturated transistor (Vce) drop?

I'm afraid I don't 'get' the circuit. You're loading the opamp
with ~1.5 mA current source. This keeps the pnp output transistor
to the neg power rail always on. Is the power opamp a buffer?
Isn't the rail to rail performance limited by the power opamp?

George H.

--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

George Herold · Mar 3, 2020

On Tuesday, March 3, 2020 at 1:33:51 PM UTC-5, John Larkin wrote:

On Tue, 3 Mar 2020 09:40:59 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Tuesday, March 3, 2020 at 12:08:52 PM UTC-5, jla...@highlandsniptechnology.com wrote:
I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

I don't know this opamp. Like the LM324 we've been discussing?

It's basically a dual version of the 324.

Does rail to rail out mean ~ 1 saturated transistor (Vce) drop?

I'd like it to go within millivolts of the positive rail. "RRO"
usually means all the way.

I'm afraid I don't 'get' the circuit. You're loading the opamp
with ~1.5 mA current source. This keeps the pnp output transistor
to the neg power rail always on. Is the power opamp a buffer?
Isn't the rail to rail performance limited by the power opamp?

The power amp is a TCA0372 as a follower, which will pull up to within
1 volt of my +24 positive rail. I just don't want to give up any more
swing in the driver amp.

Since my load on the 358 is an opamp, I guess the depletion fet could
be replaced with a pullup resistor. The opposite of what people
usually do to an LM324.

I can't add gain to the big amp, which would solve the swing problem,
because it messes up my clamp thing.

Hmm, well a resistor voltage divider here and one on the opamp.
If it's just a diode clamp, those (for me) have mussy corners and
temp. dependence anyway.

TCA0372 is amazing. A dual 1-amp opamp for 47 cents. The LM358 costs
10 cents.

I had some TCA0372's I started to use 'em for a few projects
and then didn't like something and used a spendier opamp.
This would have been audio AC stuff.

George H.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

John Larkin · Mar 3, 2020

On Tue, 3 Mar 2020 10:48:45 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Tuesday, March 3, 2020 at 1:33:51 PM UTC-5, John Larkin wrote:
On Tue, 3 Mar 2020 09:40:59 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Tuesday, March 3, 2020 at 12:08:52 PM UTC-5, jla...@highlandsniptechnology.com wrote:
I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

I don't know this opamp. Like the LM324 we've been discussing?

It's basically a dual version of the 324.

Does rail to rail out mean ~ 1 saturated transistor (Vce) drop?

I'd like it to go within millivolts of the positive rail. "RRO"
usually means all the way.

I'm afraid I don't 'get' the circuit. You're loading the opamp
with ~1.5 mA current source. This keeps the pnp output transistor
to the neg power rail always on. Is the power opamp a buffer?
Isn't the rail to rail performance limited by the power opamp?

The power amp is a TCA0372 as a follower, which will pull up to within
1 volt of my +24 positive rail. I just don't want to give up any more
swing in the driver amp.

Since my load on the 358 is an opamp, I guess the depletion fet could
be replaced with a pullup resistor. The opposite of what people
usually do to an LM324.

I can't add gain to the big amp, which would solve the swing problem,
because it messes up my clamp thing.
Hmm, well a resistor voltage divider here and one on the opamp.
If it's just a diode clamp, those (for me) have mussy corners and
temp. dependence anyway.

I want to protect my GaN fets from being reverse biased very much.
They don't exactly have substrate diodes but could be damaged by
reverse voltage drain to source.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

John Larkin · Mar 3, 2020

On Tue, 3 Mar 2020 16:22:03 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

Cheers

Phil Hobbs

I really want it to swing to the positive rail.

I guess I could add yet another opamp to stock. I'd want RRIO, dual,
32 volt supply. That's rare. OPA2990 is a candidate, 48 cents at 1K.

My fave, OPA197, is a single SOT23 for 68 cents by the reel.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Clemens Ladisch · Mar 3, 2020

bitrex wrote:

On 3/3/20 12:40 PM, George Herold wrote:
I don't know this opamp. Like the LM324 we've been discussing?

The LM358 specs look identical to an amp in a LM324N. The LM358A has somewhat better Voffset and input bias current tolerances.

http://www.ti.com/lit/pdf/sloa277 lists all 37 variants.
(But it's all the other LM358-related information in this app note that is interesting.)

Regards,
Clemens

Phil Hobbs · Mar 3, 2020

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

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

Phil Hobbs · Mar 4, 2020

On 2020-03-03 16:44, John Larkin wrote:

On Tue, 3 Mar 2020 16:22:03 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

Cheers

Phil Hob

I really want it to swing to the positive rail.

I guess I could add yet another opamp to stock. I'd want RRIO, dual,
32 volt supply. That's rare. OPA2990 is a candidate, 48 cents at 1K.

My fave, OPA197, is a single SOT23 for 68 cents by the reel.

OPA2171, about 90 cents in thousands.

OPA2140. 40V single supply, RRO, 5 nV noise, 20-Hz 1/f corner (amazing
for a JFET amp), 120 uV VOSmax, 1uV/K TCmax, 10 MHz, 20V/us. $3 in
thousands. (Otherwise it stinks.)

OPA2141, worse input accuracy, otherwise very similar. $1.50 in
thousands. Not a bad deal at all.

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

George Herold · Mar 4, 2020

On Tuesday, March 3, 2020 at 4:44:17 PM UTC-5, John Larkin wrote:

On Tue, 3 Mar 2020 16:22:03 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

Cheers

Phil Hobbs

I really want it to swing to the positive rail.

I guess I could add yet another opamp to stock. I'd want RRIO, dual,
32 volt supply. That's rare. OPA2990 is a candidate, 48 cents at 1K.

My fave, OPA197, is a single SOT23 for 68 cents by the reel.
opa2197?

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Lasse Langwadt Christense · Mar 4, 2020

onsdag den 4. marts 2020 kl. 16.31.08 UTC+1 skrev George Herold:

On Tuesday, March 3, 2020 at 4:44:17 PM UTC-5, John Larkin wrote:
On Tue, 3 Mar 2020 16:22:03 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

Cheers

Phil Hobbs

I really want it to swing to the positive rail.

I guess I could add yet another opamp to stock. I'd want RRIO, dual,
32 volt supply. That's rare. OPA2990 is a candidate, 48 cents at 1K.

My fave, OPA197, is a single SOT23 for 68 cents by the reel.
opa2197?

197/2197/4197, single/dual/quad

speff · Mar 6, 2020

On Wednesday, 4 March 2020 11:22:49 UTC-5, Lasse Langwadt Christensen wrote:

onsdag den 4. marts 2020 kl. 16.31.08 UTC+1 skrev George Herold:
On Tuesday, March 3, 2020 at 4:44:17 PM UTC-5, John Larkin wrote:
On Tue, 3 Mar 2020 16:22:03 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

Cheers

Phil Hobbs

I really want it to swing to the positive rail.

I guess I could add yet another opamp to stock. I'd want RRIO, dual,
32 volt supply. That's rare. OPA2990 is a candidate, 48 cents at 1K.

My fave, OPA197, is a single SOT23 for 68 cents by the reel.
opa2197?

197/2197/4197, single/dual/quad

OPA192 is useful for current measurement off the positive rail- 36V,
low Vos, RRIO. Worth stocking, IMHO.

A bit pricey though, ~1.20 USD in 1K.

Best regards,
Spehro Pefhany

Phil Hobbs · Mar 8, 2020

On 2020-03-05 23:40, speff wrote:

On Wednesday, 4 March 2020 11:22:49 UTC-5, Lasse Langwadt Christensen wrote:
onsdag den 4. marts 2020 kl. 16.31.08 UTC+1 skrev George Herold:
On Tuesday, March 3, 2020 at 4:44:17 PM UTC-5, John Larkin wrote:
On Tue, 3 Mar 2020 16:22:03 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-03 12:08, jlarkin@highlandsniptechnology.com wrote:

I think this will work.

https://www.dropbox.com/s/c1ivyztss1r1t10/LM358_RRO.JPG?raw=1

One charm of the old parts is that the data sheet includes a
transistor-level schematic.

Doesn't look as though the current sink on the output stage is enough to
overcome the LND250's 1.6 mA, so I sort of doubt it'll pull below V_EE +
0.6 V. Should go to the positive rail, though.

Cheers

Phil Hobbs

I really want it to swing to the positive rail.

I guess I could add yet another opamp to stock. I'd want RRIO, dual,
32 volt supply. That's rare. OPA2990 is a candidate, 48 cents at 1K.

My fave, OPA197, is a single SOT23 for 68 cents by the reel.
opa2197?

197/2197/4197, single/dual/quad

OPA192 is useful for current measurement off the positive rail- 36V,
low Vos, RRIO. Worth stocking, IMHO.

A bit pricey though, ~1.20 USD in 1K.

Best regards,
Spehro Pefhany

A pretty nice part though--40V RRIO JFET, with offset trims done after
packaging. Weirdly the N-channel input stage is ~10 dB noisier than the
P-channel one. Discrete N-cnannel parts are way quieter than P-channel
ones.

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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