Reply by Jim Thompson●September 15, 20132013-09-15
On Sun, 15 Sep 2013 13:30:52 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>On Sun, 15 Sep 2013 12:51:45 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>>On Sun, 15 Sep 2013 11:53:45 -0700, Fred Abse
>><excretatauris@invalid.invalid> wrote:
>>
>>>On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
>>>
>>>> Mike tells me that the 1028N model wasn't accurate,
>>>
>>>Comparing the datasheet, and the models, I find that the
>>>pinouts don't match, output on the wrong pin (5), should be 6.
>>>
>>>Small signal transient response of the LT1028 model shows far too much
>>>overshoot, compared with datasheet waveform photograph, under stated
>>>conditions, and looks much more like LT1128.
>>>
>>>Both using 10ns risetime test pulse.
>>>
>>>I assume that the datasheet is authoritative. The real device looks much nicer
>>>than the model predicts.
>>>
>>>Not what we've come to expect from LTC. At least they came clean.
>>
>>There's no LT1028 (or LT1128) model in the latest release, probably
>>going encrypted :-(
>>
>> ...Jim Thompson
>
>I did a full delete/reinstall of LT Spice yesterday, and it has three LT1028
>versions in the "opamps" library. And one 1128.
Found it. Screwed up the date setting in my search engine :-(
It's virtually 100% behavioral, plus a whole pile of "noiseless"
resistors.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by Jim Thompson●September 15, 20132013-09-15
On Sun, 15 Sep 2013 13:30:52 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>On Sun, 15 Sep 2013 12:51:45 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>>On Sun, 15 Sep 2013 11:53:45 -0700, Fred Abse
>><excretatauris@invalid.invalid> wrote:
>>
>>>On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
>>>
>>>> Mike tells me that the 1028N model wasn't accurate,
>>>
>>>Comparing the datasheet, and the models, I find that the
>>>pinouts don't match, output on the wrong pin (5), should be 6.
>>>
>>>Small signal transient response of the LT1028 model shows far too much
>>>overshoot, compared with datasheet waveform photograph, under stated
>>>conditions, and looks much more like LT1128.
>>>
>>>Both using 10ns risetime test pulse.
>>>
>>>I assume that the datasheet is authoritative. The real device looks much nicer
>>>than the model predicts.
>>>
>>>Not what we've come to expect from LTC. At least they came clean.
>>
>>There's no LT1028 (or LT1128) model in the latest release, probably
>>going encrypted :-(
>>
>> ...Jim Thompson
>
>I did a full delete/reinstall of LT Spice yesterday, and it has three LT1028
>versions in the "opamps" library. And one 1128.
I did an "update" two days ago, I'll try again. Thanks for the tip.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by John Larkin●September 15, 20132013-09-15
On Sun, 15 Sep 2013 15:52:53 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
>On 09/15/2013 02:53 PM, Fred Abse wrote:
>> On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
>>
>>> Mike tells me that the 1028N model wasn't accurate,
>>
>> Comparing the datasheet, and the models, I find that the
>> pinouts don't match, output on the wrong pin (5), should be 6.
>>
>> Small signal transient response of the LT1028 model shows far too much
>> overshoot, compared with datasheet waveform photograph, under stated
>> conditions, and looks much more like LT1128.
>>
>> Both using 10ns risetime test pulse.
>>
>> I assume that the datasheet is authoritative. The real device looks much nicer
>> than the model predicts.
>>
>> Not what we've come to expect from LTC. At least they came clean.
>>
>
>The LT1028 datasheet is a travesty. You'd never guess from the noise
>plot that there's a big noise peak at 300 kHz and another one (I'm told)
>out around 2 MHz. One of the more egregious bits of specsmanship I've
>seen--right up there with chopamp datasheets. I ripped them over it
>once, after discovering that nasty peak experimentally, and was told
>something along the lines of
>
>"Our marketing department decided that this was really an audio part, so
>the datasheet has all the data relevant to audio uses. Nobody cares
>about 300 kHz noise in audio."
>
>The audio noise level rose fairly dramatically at about that point. ;)
>
>'The Hitchhiker's Guide to the Galaxy defines the Marketing Division of
>the Sirius Cybernetics Corporation as "A bunch of mindless jerks who
>will be the first against the wall when the revolution comes."'
>
>(Second against the wall will be the HR department, of course.)
>
>Cheers
>
>Phil Hobbs
I've used LT1028s in NMR gradient drivers, but bandwidth there is usually in the
30 KHz range. Got lucky, I guess.
Funny how IC people leave bugs around forever; they rarely fix things, and often
deny the problems. I'm sure there are cases where hundreds of users found the
same bug, over many years, at great expense.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply by John Larkin●September 15, 20132013-09-15
On Sun, 15 Sep 2013 12:51:45 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>On Sun, 15 Sep 2013 11:53:45 -0700, Fred Abse
><excretatauris@invalid.invalid> wrote:
>
>>On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
>>
>>> Mike tells me that the 1028N model wasn't accurate,
>>
>>Comparing the datasheet, and the models, I find that the
>>pinouts don't match, output on the wrong pin (5), should be 6.
>>
>>Small signal transient response of the LT1028 model shows far too much
>>overshoot, compared with datasheet waveform photograph, under stated
>>conditions, and looks much more like LT1128.
>>
>>Both using 10ns risetime test pulse.
>>
>>I assume that the datasheet is authoritative. The real device looks much nicer
>>than the model predicts.
>>
>>Not what we've come to expect from LTC. At least they came clean.
>
>There's no LT1028 (or LT1128) model in the latest release, probably
>going encrypted :-(
>
> ...Jim Thompson
I did a full delete/reinstall of LT Spice yesterday, and it has three LT1028
versions in the "opamps" library. And one 1128.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply by Phil Hobbs●September 15, 20132013-09-15
On 09/15/2013 02:53 PM, Fred Abse wrote:
> On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
>
>> Mike tells me that the 1028N model wasn't accurate,
>
> Comparing the datasheet, and the models, I find that the
> pinouts don't match, output on the wrong pin (5), should be 6.
>
> Small signal transient response of the LT1028 model shows far too much
> overshoot, compared with datasheet waveform photograph, under stated
> conditions, and looks much more like LT1128.
>
> Both using 10ns risetime test pulse.
>
> I assume that the datasheet is authoritative. The real device looks much nicer
> than the model predicts.
>
> Not what we've come to expect from LTC. At least they came clean.
>
The LT1028 datasheet is a travesty. You'd never guess from the noise
plot that there's a big noise peak at 300 kHz and another one (I'm told)
out around 2 MHz. One of the more egregious bits of specsmanship I've
seen--right up there with chopamp datasheets. I ripped them over it
once, after discovering that nasty peak experimentally, and was told
something along the lines of
"Our marketing department decided that this was really an audio part, so
the datasheet has all the data relevant to audio uses. Nobody cares
about 300 kHz noise in audio."
The audio noise level rose fairly dramatically at about that point. ;)
'The Hitchhiker's Guide to the Galaxy defines the Marketing Division of
the Sirius Cybernetics Corporation as "A bunch of mindless jerks who
will be the first against the wall when the revolution comes."'
(Second against the wall will be the HR department, of course.)
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Reply by Jim Thompson●September 15, 20132013-09-15
On Sun, 15 Sep 2013 11:53:45 -0700, Fred Abse
<excretatauris@invalid.invalid> wrote:
>On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
>
>> Mike tells me that the 1028N model wasn't accurate,
>
>Comparing the datasheet, and the models, I find that the
>pinouts don't match, output on the wrong pin (5), should be 6.
>
>Small signal transient response of the LT1028 model shows far too much
>overshoot, compared with datasheet waveform photograph, under stated
>conditions, and looks much more like LT1128.
>
>Both using 10ns risetime test pulse.
>
>I assume that the datasheet is authoritative. The real device looks much nicer
>than the model predicts.
>
>Not what we've come to expect from LTC. At least they came clean.
There's no LT1028 (or LT1128) model in the latest release, probably
going encrypted :-(
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by Fred Abse●September 15, 20132013-09-15
On Sat, 14 Sep 2013 14:40:42 -0700, John Larkin wrote:
> Mike tells me that the 1028N model wasn't accurate,
Comparing the datasheet, and the models, I find that the
pinouts don't match, output on the wrong pin (5), should be 6.
Small signal transient response of the LT1028 model shows far too much
overshoot, compared with datasheet waveform photograph, under stated
conditions, and looks much more like LT1128.
Both using 10ns risetime test pulse.
I assume that the datasheet is authoritative. The real device looks much nicer
than the model predicts.
Not what we've come to expect from LTC. At least they came clean.
--
"Design is the reverse of analysis"
(R.D. Middlebrook)
Reply by John Larkin●September 14, 20132013-09-14
On Sat, 14 Sep 2013 19:39:36 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
>On 9/14/2013 5:40 PM, John Larkin wrote:
>> On Sat, 14 Sep 2013 13:53:48 -0700, Fred Abse <excretatauris@invalid.invalid>
>> wrote:
>>
>>> On Sat, 14 Sep 2013 12:51:04 -0700, John Larkin wrote:
>>>
>>>>
>>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Amps/LT1028N.jpg
>>>>
>>>> LT1028 works, but LT1028N, the one that brings out the comp pin, doesn't.
>>>
>>> Found an old library file in my backup directory, with an LT1028
>>> subcircuit. Looks like it's obsolete. D'you want the subcircuit?
>>
>> Mike tells me that the 1028N model wasn't accurate, so he deleted it. Part of
>> the 1028N stuff was apparently still in my lib files, and in the opamp selection
>> list. He suggested a resync, which didn't change things, so I did a full
>> remove/reinstall, which *did* delete it.
>>
>> The new 1028 model is supposed to be better, but it doesn't bring out the
>> overcomp pin, which the 1028N model did, and I'd like to use.
>>
>> I'd like to use the 1028 as a follower, and it's not stable that way. I figured
>> I could tune the overcomp cap to make it stable and to make it really gain/phase
>> flat to to a MHz or two, but I can't sim that now.
>>
>> Most opamps, as followers, have a small gain peak before they roll off. Adding a
>> RC lowpass downstream can tune that, at the expense of output impedance and one
>> more part.
>>
>> Life sucks.
>>
>>
>The LT1028 isn't the best option for a low noise op amp these days,
>except for special cases. It has a nasty noise and compensation
>whoopdedoo around 300 kHz that the data sheet doesn't come clean about
>(at least the one I have doesn't). How about a nice well behaved
>ADA4898 or ADA4899?
>
>Cheers
>
>Phil Hobbs
OK, thanks, I'll look at those.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Reply by Phil Hobbs●September 14, 20132013-09-14
On 9/14/2013 5:40 PM, John Larkin wrote:
> On Sat, 14 Sep 2013 13:53:48 -0700, Fred Abse <excretatauris@invalid.invalid>
> wrote:
>
>> On Sat, 14 Sep 2013 12:51:04 -0700, John Larkin wrote:
>>
>>>
>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Amps/LT1028N.jpg
>>>
>>> LT1028 works, but LT1028N, the one that brings out the comp pin, doesn't.
>>
>> Found an old library file in my backup directory, with an LT1028
>> subcircuit. Looks like it's obsolete. D'you want the subcircuit?
>
> Mike tells me that the 1028N model wasn't accurate, so he deleted it. Part of
> the 1028N stuff was apparently still in my lib files, and in the opamp selection
> list. He suggested a resync, which didn't change things, so I did a full
> remove/reinstall, which *did* delete it.
>
> The new 1028 model is supposed to be better, but it doesn't bring out the
> overcomp pin, which the 1028N model did, and I'd like to use.
>
> I'd like to use the 1028 as a follower, and it's not stable that way. I figured
> I could tune the overcomp cap to make it stable and to make it really gain/phase
> flat to to a MHz or two, but I can't sim that now.
>
> Most opamps, as followers, have a small gain peak before they roll off. Adding a
> RC lowpass downstream can tune that, at the expense of output impedance and one
> more part.
>
> Life sucks.
>
>
The LT1028 isn't the best option for a low noise op amp these days,
except for special cases. It has a nasty noise and compensation
whoopdedoo around 300 kHz that the data sheet doesn't come clean about
(at least the one I have doesn't). How about a nice well behaved
ADA4898 or ADA4899?
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
Reply by John Larkin●September 14, 20132013-09-14
On Sat, 14 Sep 2013 13:33:41 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:
>On Saturday, September 14, 2013 9:51:04 PM UTC+2, John Larkin wrote:
>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Amps/LT1028N.jpg
>>
>>
>>
>> LT1028 works, but LT1028N, the one that brings out the comp pin, doesn't.
>>
>
>
>where have you found LT1028N? I can't find it int the latest version, and when looking at the linear site it doesn't even exist
>
>-Lasse
The 1028N model was a version of the 1028 model that brought out the overcomp
pin. All physical LT1028s have that pin, but Spice doesn't support it any more.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators