round () function on AC measurements does crash on old versions and just delivers zero at latest version
using round to get better readable results (e.g. mV's with one further number after the dot) in the measurements does not work for me in AC measurements while it works fine for TRAN.
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running .AC the following statements bring the below listed results
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.OPTIONS meascplxfmt=polar
.MEAS V_ACOMP_max_IC7_p18_mV ? ? ? ? ? ? ? ? ? ?PARAM (V_ACOMP_max_IC7_p18*1000*10)/10
.MEAS V_ACOMP_max_IC7_p18_mV_2 ? ? ? ? ? ? ? ? ? ?PARAM round(mag((V_ACOMP_max_IC7_p18*1000*10)/10))
.MEAS AC V_ACOMP_max_IC7_p18_mV_3 ? ? ? ? ? ? ? ? PARAM round(mag((V_ACOMP_max_IC7_p18*1000*10)/10))
leads to
v_acomp_max_ic7_p18_mv: (V_ACOMP_max_IC7_p18*1000*10)/10=(24.2389660125,0?°)
v_acomp_max_ic7_p18_mv_2: round(mag((V_ACOMP_max_IC7_p18*1000*10)/10))=(0,0?°)
v_acomp_max_ic7_p18_mv_3: round(mag((V_ACOMP_max_IC7_p18*1000*10)/10))=(0,0?°)
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In former versions e.g. 24.0.12 using round() even crashed and said: this is a bug, please report it.
Now with 24.1.8 it does not crash but reports zero...but maybe I am doin wrong because I don't get converted (not even with mag() ) this cartesian numbers to normal values.
Also the ASCII character in front of ° looks weired since new version installed.
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Dave,
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When you loaded the schematic, and View > Visible Traces didn't work, was the .RAW file in the same place?
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That would make LTspice unable to find it.? That's the only thing I can think of.
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Andy
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To follow up, loading a .raw file directly then works to execute .meas files.
So, answering my original question, after a complete Run, save (in Settings) the raw file(s), or make a copy, while the simulation is still in the app,
Reloading that .raw file gives access to the large data from a long and multipart simulation.
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Dave
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Show quoted text
From: [email protected] <[email protected]>
On Behalf Of Bell, Dave via groups.io
Sent: Monday, May 19, 2025 5:27 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Execute .meas file
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I closed LTspice along with the schematic, then opened just the sch.
View, either by right-clicking the schematic, or from the View menu option, has Visible Traces grayed out until a Run.
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I haven’t yet tried opening a RAW file directly. That’s next…
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You can also open a .RAW file directly into LTspice, and see all your waveforms, and maybe run .MEAS scripts.? But doing it that way, they won't be associated with a schematic.? To re-establish the ability to click on schematic nets to
see waveforms, you have to open the schematic first, then View > Visible Traces.
I went my first few years using LTspice, not aware that I should do that - until Helmut pointed it out.
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I closed LTspice along with the schematic, then opened just the sch.
View, either by right-clicking the schematic, or from the View menu option, has Visible Traces grayed out until a Run.
?
I haven’t yet tried opening a RAW file directly. That’s next…
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toggle quoted message
Show quoted text
From: [email protected] <[email protected]>
On Behalf Of Andy I via groups.io
Sent: Monday, May 19, 2025 5:00 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Execute .meas file
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You can also open a .RAW file directly into LTspice, and see all your waveforms, and maybe run .MEAS scripts.? But doing it that way, they won't be associated with a schematic.? To re-establish the ability to click on schematic nets to
see waveforms, you have to open the schematic first, then View > Visible Traces.
I went my first few years using LTspice, not aware that I should do that - until Helmut pointed it out.
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You can also open a .RAW file directly into LTspice, and see all your waveforms, and maybe run .MEAS scripts.? But doing it that way, they won't be associated with a schematic.? To re-establish the ability to click on schematic nets to see waveforms, you have to open the schematic first, then View > Visible Traces.
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I went my first few years using LTspice, not aware that I should do that - until Helmut pointed it out.
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Andy
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Thanks, Andy!
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- Yeah, the .RAW is what I thought.
But if I rename that with a different extension, it still runs the script.
In the Help. there’s a hint that it can also derive data from the Plot.
- Ah-hah!? I will try that.
That would load everything back into memory.
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Show quoted text
From: [email protected] <[email protected]>
On Behalf Of Andy I via groups.io
Sent: Monday, May 19, 2025 3:33 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Execute .meas file
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I am not in the habit of running .MEAS scripts, so my answers may or may not help
- Which temporary file(s) do we need to keep, if we want to return to a model and execute one of several .meas scripts?
I would not think you need any temporary files.? I could be wrong, but I think you need only the .MEAS script files themselves, and of course the .RAW output file.
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2. Is there a way (maybe in batch mode?) to execute a meas script
without re-running the simulation?
If you come back to a previously run simulation and want to examine the results without re-running the simulation, use Right-click > View > Visible Traces.? That loads the .RAW file back into LTspice and you should be back to where you
were when the simulation completed.? I'm assuming that would be all you need to do before executing .MEAS scripts.
The alternative to Right-click is: View (menu bar) > Visible Traces.? The hotkeys are Alt-V-V (in older LTspice versions).
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I am not in the habit of running .MEAS scripts, so my answers may or may not help
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Bell, Dave wrote:
- Which temporary file(s) do we need to keep, if we want to return to a model and execute one of several .meas scripts?
I would not think you need any temporary files.? I could be wrong, but I think you need only the .MEAS script files themselves, and of course the .RAW output file.
2. Is there a way (maybe in batch mode?) to execute a meas script without re-running the simulation?
If you come back to a previously run simulation and want to examine the results without re-running the simulation, use Right-click > View > Visible Traces.? That loads the .RAW file back into LTspice and you should be back to where you were when the simulation completed.? I'm assuming that would be all you need to do before executing .MEAS scripts.
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The alternative to Right-click is: View (menu bar) > Visible Traces.? The hotkeys are Alt-V-V (in older LTspice versions).
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Andy
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On Mon, May 19, 2025 at 06:02 PM, Pietro wrote:
I am writing this post not because I do not know how to connect the 2 missing pins but because I have doubts that the component in LTspice LT1680 is wrong and maybe there is a valid file to replace in the simulation.
I am not employed by Analog Devices, but I can say with high confidence that the LTspice LT1680 model is correct and it simply did not include those two pins because they aren't needed in the simulations.
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Vref is an internally generated DC voltage that needs a bypass capacitor connected to it, so it has a pin where you can connect one.? You won't use it for anything else, and the SPICE simulation doesn't need it.
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I do not know much about the SYNC pin, except that it seems to be optional, and they recommend grounding it if it is not used.? From the signal name, I am guessing it may have something to do with synchronizing multiple LT1680 parts together.? If you are doing that, then make sure to read the datasheet carefully.? My guess is that they did not include it in the SPICE model because it is rarely ever used, and it likely won't affect the simulation of your DC voltages.
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It is not unusual for SPICE models to omit pins that are rarely used.? I guess this is the first time you saw that.
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Andy
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I mentioned this already, but I think it is worth a bit more elaboration.??John Woodgate wrote:
... but it is a problem when passing data to a PC layout app.
SPICE/LTspice simulations are never meant to constitute the full and complete design database for a circuit layout.? Yes, you can take a schematic in LTspice and export it to a file that can be read by a PC layout program, and that's fine.? But you should ALWAYS assume that the LTspice-generated netlist does not have some things that are necessary for the physical layout, because they were not needed to simulate the circuit.? It should ALWAYS be assumed that modifications and touch-ups will be needed, after the circuit is ported into a PCB layout system.? Anyone who takes an LTspice simulation, exports it to a layout program, and blindly uses it that way is "shooting themselves in the foot".
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The SPICE models for many ICs are not 100% complete and do not include some physical pins.? Some LTspice models omit pins and the functions that connect to those pins, because almost no design engineer ever needs to simulate those parts of the circuit.? So they are omitted from the LTspice model and from the LTspice simulation.? But the real IC has them, and you may need to do something with those pins in the physical design even though they were not a part of the simulation.
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Andy I
I studied the datasheet, I know that it is my final responsibility to make design choices according to my skills, but I believe that the community serves the purpose of sharing problems and solutions and maybe this problem has already been solved by some other member since it is a component from the year 2004 (21 years).
I am writing this post not because I do not know how to connect the 2 missing pins but because I have doubts that the component in LTspice LT1680 is wrong and maybe there is a valid file to replace in the simulation.
(As often happens).
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Oops, my reply was sent prematurely.? I started writing:
Did you have questions about the naming differences with any of the other pins?
I concluded that "Iavg" and "Iave" were probably the same, and that "Vfb" and "FB" are probably the same.? But again, it is your job to understand what each of those pins actually does and how to use them.? That should make it obvious which pin is which.
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Are there other pin names you found confusing?
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Andy
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On Mon, May 19, 2025 at 05:28 PM, Pietro wrote:
Okay, that's fine, but then, when I have to design and build it all, how will I connect the missing pins?
And then, will it work properly?
These are my doubts.
Who is the design engineer?? If that is you, then you must be the master of your design.? You need to take full responsibility for understanding what the circuit does and how every part of it works.
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If you seriously don't know what to do with the extra two pins because you couldn't include them in your LTspice simulation, then it is your job to understand how those two pins work, and how they should be connected, and whether they can be ignored by not connecting to them.? Chances are they can't be ignored, and probably should be connected to something.
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When I compared the datasheet with the LTspice symbol, the only two pins I could not match up with the symbol were:
- Pin 8 = Vref
- Pin 15 = SYNC
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Now here is where your engineering skills become important.? What do those two pins do?? What does the datasheet say about them?? In one figure in the datasheet it shows one pin connected to ground, and the other pin connected to a bypass capacitor.? But it is your job to read the datasheet and understand what is the right thing to do with those two pins.
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Most datasheets from Analog Devices have fairly detailed about what every pin does, and how to use it.? Read the datasheet to find out.
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Did you have questions about the naming differences with any of the other pins?
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Andy
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Lunedì 19 maggio 2025 alle 23:12, John Woodgate ha scritto:
If you want to take a look, I uploaded an image file in the photo section.
Okay, that's fine, but then, when I have to design and build it all, how will I connect the missing pins?
And then, will it work properly?
These are my doubts.
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Sì, scusa. Mi sono confuso.
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[Translation to English by Moderator:]
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Yes, sorry. I got confused.
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Your upload is helpful, but you must post in
English. Google Translate is your friend.
On 2025-05-19 22:04, Pietro via
groups.io wrote:
Se vuoi dare un'occhiata,
ho caricato un file immagine nella sezione foto.
Ok, va bene, ma poi, quando
dovrò progettare e costruire il tutto, come collegherò i pin
mancanti?
E ??poi, funzionerà
correttamente?
Questi sono i miei dubbi.
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
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LTspice is not meant for circuit layout.? When it is used for that, it MUST be assumed that "touch-up" is probably needed.
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Andy
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Sorry, but please use English only in this group.
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FYI, many op-amp's have Balance adjustment pins, but most of their SPICE models omit them.? Most circuits that used them did not connect to those pins anyway.
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Andy
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That is OK for simulation: commoned pins and
NC pins can be left of the symbol and model, but it is a problem
when passing data to a PC layout app.
On 2025-05-19 21:59, Andy I via
groups.io wrote:
I have not looked at yet - but it is very common for SPICE
models to have fewer pins than actual pins.? Also, pin names
often vary.
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Andy
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
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Se vuoi dare un'occhiata, ho caricato un file immagine nella sezione foto.
Ok, va bene, ma poi, quando dovrò progettare e costruire il tutto, come collegherò i pin mancanti?
E ??poi, funzionerà correttamente?
Questi sono i miei dubbi.
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[Mod note:? Please use only English in this group.? A translation to English is below:]
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If you want to take a look, I uploaded an image file in the photo section.
Okay, that's fine, but then, when I have to design and build it all, how will I connect the missing pins?
And then, will it work properly?
These are my doubts.
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I have not looked at yet - but it is very common for SPICE models to have fewer pins than actual pins.? Also, pin names often vary.
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Andy
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Bell, Dave
Pietro
John Woodgate