Re: Behavioral source timestep limits ?

Hello, Andy:

Let me ask this:? What are you trying to do?? Why add the Bv sources?

Just some quick transfer trying for compensation to a newer shape as the secondary reference, concurrently with the first priority feedback still connected.

The description expressed in the fashion of could apply to any topology.

Thank you for the suggestions.

Best regards.

Re: Problem with using LM4562

#108500

Hello.

I offered to Google translator another translation option:

operating point ?==> operatsionnaya tochka?(in Russian in Latin letters)

Thanks to Andy for the clarification.

Bordodynov.

?

14.11.2018, 23:58, "John Woodgate jmw@... [LTspice]" <ltspice@...>:

Show quoted text

?
I looked at Electropedia, publicly available from the IEC web site .? It can be helpful because it gives equivalent terms in other languages (Russian is not very often included.). However, in this case (by no means unique) it is perhaps not much help:

operating point
working point ???
the point on the family of characteristic curves corresponding to the average voltages or currents of the electrodes in the presence of a signal

Another definition, which is also not very helpful:

operating point ???
point on a characteristic curve representing the values of variable quantities at which a system is operating

John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates 
Rayleigh, Essex UK
On 2018-11-14 17:29, Andy ai.egrps@... [LTspice] wrote:

?

Jerry Lee Marcel wrote, "Can you elaborate on this difference (for us non-native)."

To me, from what I was taught in school and heard throughout my career, "operating point" is very specific and means the set of voltages and currents of the circuit, or the static bias conditions in the circuit.

"Working point" has no special meaning.? I guess it could mean anything.? I have never seen the expression "working point" used to mean the "operating point" of a circuit.

In other words, for circuit simulation, and only speaking from my electronics experience:

- "Operating point" means the bias conditions

- "Working point" is ambiguous or undefined

It makes sense that a translator might translate them the same, even if they do not mean the same thing to an American, English speaking electrical engineer.

That's why I encourage Bordodynov to use "operating point" in the English description.? Months from now, if someone comes across his file, if the file's description says "working point" they might not know what it is.? If it says "operating point" they know what it is probably about.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108498

An interesting thing......is ...

Those phenomemon in other software eg: PSIM, the math parsing won't take any effect with those loading effect. This might confused me to do those kind of contradiction, if I ran both simulators in a same while. I can't believe , it took me many minutes to recall why I do this kind of mistake (neglected the loading effect), then I done some hard effort to figure out the way why I connect wires like this, to the final, because the different fashion in different simulators.

Some strange experience.

---In LTspice@..., <ericsson.sunshine@...> wrote :

Hi, Andy:

Sorry, I saw the blindpoint.

The BV didn't the connection of two nodes, it's a new voltage source.

So the errOP's peripheral won't work as expect, after I added a 10K resistor between the BV and IC's 'Vsense', the simulation woks as expect.

I think I know what's going on.

Sorry for the disturbance,

Best regards.

---In LTspice@..., <ericsson.sunshine@...> wrote :

Hi, Andy:

Thank you for the replies, I'm sorry, it's too rush, so made this mistake.

I have uploaded another example which uses the LT1249, typically the FB is resistor divided, the current sinked into the IC's normally treated very tiny, the voltage reference almost viewed as the voltage divided by resistors.

The new example is more approaching to what problem I described. Is that caused by the load effect ? I mean the current sinked into the IC, or the errop's peripherals ,those affect the difference of the result ?

What do you think of those ? Could it be solved by other methods ? Bypass with other device , models or ... ?

Thank you for the opinions.

Have a nice day!

---In LTspice@..., <ai.egrps@...> wrote :

Ericsson.sunshine,

Regarding your circuit in 20181115_BV,BI behavioral device FB pin test failure desc.zip:

I think you forgot about the current through R2 and the voltage drop across it.

The original circuit had about 83uA current through R2.? So there was 11V voltage drop across R2.? The altered circuit has no current through R2.? Therefore, the voltage on node FB would be 11V greater than it was in the original circuit, if everything else was the same.? That's going to cause a big difference.

Looking quickly at the LT3580 datasheet, I think they depend on a significant voltage drop across the feedback resistor.? The current into the part's "FB" pin is tightly controlled, within 2%-3%, and the normal voltage on that pin is small, only +1.215V.? In your simulation it has?+4.7V (+7.1V at first) on the pin which is too much and could kill the LT3580.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108499

Ericsson.sunshine,

Without running any simulation yet, it looks like your second uploaded example (LT1249) could be a problem too.

The Vsense and VAout pins are the input and output pins of the error amplifier.? The original circuit has an RC network (C1, C2, R1) in that feedback loop, where it provides AC feedback around that amp.? Your added Bv source is applied directly to the Vsense pin, so it shorts out that feedback.? That might be a big change.

I don't think there is very much loading difference on the resistors (R5 & R6) with B1 added.? But I'm sure there is a little.

Running the simulation, it looks like the output voltage is still about right, but it is more "ragged" with a sawtooth shape.? This is only a first guess, but I'm thinking the error amplifier is not stable without its AC feedback path, and it's hunting back and forth.? Indeed, in the original circuit VAout stabilizes at around?+4V with a little bit of variation; but in the modified circuit, it swings wildly between 5.5V and almost 12V, and doesn't settle down.

Every change has a consequence.

Let me ask this:? What are you trying to do?? Why add the Bv sources?

I can't answer your last questions (e.g., "Could it be solved by other methods?") without knowing what you are trying to do.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108497

Hi, Andy:

Sorry, I saw the blindpoint.

The BV didn't the connection of two nodes, it's a new voltage source.

So the errOP's peripheral won't work as expect, after I added a 10K resistor between the BV and IC's 'Vsense', the simulation woks as expect.

I think I know what's going on.

Sorry for the disturbance,

Best regards.

---In LTspice@..., <ericsson.sunshine@...> wrote :

Hi, Andy:

Thank you for the replies, I'm sorry, it's too rush, so made this mistake.

I have uploaded another example which uses the LT1249, typically the FB is resistor divided, the current sinked into the IC's normally treated very tiny, the voltage reference almost viewed as the voltage divided by resistors.

The new example is more approaching to what problem I described. Is that caused by the load effect ? I mean the current sinked into the IC, or the errop's peripherals ,those affect the difference of the result ?

What do you think of those ? Could it be solved by other methods ? Bypass with other device , models or ... ?

Thank you for the opinions.

Have a nice day!

---In LTspice@..., <ai.egrps@...> wrote :

Ericsson.sunshine,

Regarding your circuit in 20181115_BV,BI behavioral device FB pin test failure desc.zip:

I think you forgot about the current through R2 and the voltage drop across it.

The original circuit had about 83uA current through R2.? So there was 11V voltage drop across R2.? The altered circuit has no current through R2.? Therefore, the voltage on node FB would be 11V greater than it was in the original circuit, if everything else was the same.? That's going to cause a big difference.

Looking quickly at the LT3580 datasheet, I think they depend on a significant voltage drop across the feedback resistor.? The current into the part's "FB" pin is tightly controlled, within 2%-3%, and the normal voltage on that pin is small, only +1.215V.? In your simulation it has?+4.7V (+7.1V at first) on the pin which is too much and could kill the LT3580.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108496

Hi, Andy:

Thank you for the replies, I'm sorry, it's too rush, so made this mistake.

I have uploaded another example which uses the LT1249, typically the FB is resistor divided, the current sinked into the IC's normally treated very tiny, the voltage reference almost viewed as the voltage divided by resistors.

The new example is more approaching to what problem I described. Is that caused by the load effect ? I mean the current sinked into the IC, or the errop's peripherals ,those affect the difference of the result ?

What do you think of those ? Could it be solved by other methods ? Bypass with other device , models or ... ?

Thank you for the opinions.

Have a nice day!

---In LTspice@..., <ai.egrps@...> wrote :

Ericsson.sunshine,

Regarding your circuit in 20181115_BV,BI behavioral device FB pin test failure desc.zip:

I think you forgot about the current through R2 and the voltage drop across it.

The original circuit had about 83uA current through R2.? So there was 11V voltage drop across R2.? The altered circuit has no current through R2.? Therefore, the voltage on node FB would be 11V greater than it was in the original circuit, if everything else was the same.? That's going to cause a big difference.

Looking quickly at the LT3580 datasheet, I think they depend on a significant voltage drop across the feedback resistor.? The current into the part's "FB" pin is tightly controlled, within 2%-3%, and the normal voltage on that pin is small, only +1.215V.? In your simulation it has?+4.7V (+7.1V at first) on the pin which is too much and could kill the LT3580.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108495

Ericsson.sunshine,

Regarding your circuit in 20181115_BV,BI behavioral device FB pin test failure desc.zip:

I think you forgot about the current through R2 and the voltage drop across it.

The original circuit had about 83uA current through R2.? So there was 11V voltage drop across R2.? The altered circuit has no current through R2.? Therefore, the voltage on node FB would be 11V greater than it was in the original circuit, if everything else was the same.? That's going to cause a big difference.

Looking quickly at the LT3580 datasheet, I think they depend on a significant voltage drop across the feedback resistor.? The current into the part's "FB" pin is tightly controlled, within 2%-3%, and the normal voltage on that pin is small, only +1.215V.? In your simulation it has?+4.7V (+7.1V at first) on the pin which is too much and could kill the LT3580.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108494

Ericsson.sunshine, that paragraph (from LTspice's Help) about "instantaneous feedback", applies to .TRAN analysis too.

The last sentence mentions .AC analysis, to say that it is not only .TRAN analysis, it also applies to .AC analysis.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108493

Hi, Andy:

Thank you for your replies, I have read the documentation in help or on-line, neither could I understand it very well , though it cost me much looooong time trying to read it for the first time, made me step back thinking if I should read it for the 2nd time.

I have uploaded an example file, which contain 2 simulation files, one is from the original jigs, the other is added the BV=V(FB) simply doing the signal unity transferring, but the result is much different, I don't know if this could completely represent the original question I ask (due to the confidential reason), but it shows similar phenomemon, -> logically nothing changed, but severe result happens.

The file named "20181115_BV,BI behavioral device FB pin test failure desc.zip" uploaded at the temp folder. If you could kindly take a look at it and try it.

? ? "However, it is assumed that the circuit element current is varying quasi-statically, that is, there is no instantaneous feedback between the current through the referenced device and the behavioral source output. Similarly, any ac component of such a device current is assumed to be zero in a small signal linear .AC analysis."

I guess this means, the .AC analysis is based on the DC biased point, then doing small signal analysis, and the small signal injection doesn't include the BV,BI which is not typical SPICE devices. But my question was ran in .TRAN analysis.

Thank you very much.

Have a nice day!

---In LTspice@..., <ai.egrps@...> wrote :

ericsson.sunshine asked about (I think) timestep effects, and Behavioral sources, and feedback.

I can't figure out what you are asking.??However, I guess the answer is to say yes, there can be limitations when adding anything to a simulation.? Everything interacts.? There might be more limitations when considering B-sources.

Regarding timestep and Bv/Bi sources, take a careful look at the tripdv and tripdt parameters of those functions.??The Help file description says little more than "Tripdv and tripdt control (time)step rejection."??There is a more complete explanation (although one that is almost as confusing) on the LTwiki webpage, here:

? ??

I have read that description a dozen times, but I still don't understand it.

Regarding feedback signals, you should be aware that the inputs to a B-source should not depend on instantaneous feedback from its own output.? This is mentioned on the Help page, this way:

? ? "However, it is assumed that the circuit element current is varying quasi-statically, that is, there is no instantaneous feedback between the current through the referenced device and the behavioral source output. Similarly, any ac component of such a device current is assumed to be zero in a small signal linear .AC analysis."

It is not clear exactly what that means.? It SEEMS to say that you shouldn't use a B-source anywhere near a feedback loop -- which seems like an extreme restriction.? On the other hand, the restriction stated above was given in the context of using pin currents as the inputs to the B-source, which would imply that maybe the restriction only applies to B-source formulas that use pin currents of the form Ib(Q1) or Id(M5), and not in general to all B-sources.? Regardless, I have come across mention of this restriction before, about instantaneous feedback and signals that vary faster than "quasi-statically" (meaning: they can only be DC or changing very slowly).

So I can't answer your question directly (because I don't understand the question).? But I can say this:

?- B-sources have some restrictions when used in feedback circuits;

?- B-sources have some restrictions even when not used in feedback circuits, regarding what signals can be used as their "inputs";

?- B-sources can have issues with timestep control;

?- B-sources have extra parameters to help remedy the problems with timestep control.

Regards,

Andy

Modeling ceramic capacitors vs. voltage, temperature, and frequency

#108492

This might be of interest to some people here.? There is a new article:

"SPICE Models for Ceramic Capacitors ... (Nearly) Better Than the Real Thing?"

It's written by Alain Stas, of Vishay and a member here, and it's at the "Planet Analog" website.? Alain has written other articles that also use LTspice.

Unfortunately, the graphics are barely readable.? 'Planet Analog' does its readers a disservice by not making either the schematics or the original graphics files available for download.

Regards,

Andy

Re: Problem with using LM4562

#108489

开云体育

I looked at Electropedia, publicly available from the IEC web site .? It can be helpful because it gives equivalent terms in other languages (Russian is not very often included.). However, in this case (by no means unique) it is perhaps not much help:

operating point
working point ???
the point on the family of characteristic curves corresponding to the average voltages or currents of the electrodes in the presence of a signal

Another definition, which is also not very helpful:

operating point ???
point on a characteristic curve representing the values of variable quantities at which a system is operating

John Woodgate OOO-Own Opinions Only

J M Woodgate and Associates 
Rayleigh, Essex UK

On 2018-11-14 17:29, Andy ai.egrps@... [LTspice] wrote:

Show quoted text

?

Jerry Lee Marcel wrote, "Can you elaborate on this difference (for us non-native)."

To me, from what I was taught in school and heard throughout my career, "operating point" is very specific and means the set of voltages and currents of the circuit, or the static bias conditions in the circuit.

"Working point" has no special meaning.? I guess it could mean anything.? I have never seen the expression "working point" used to mean the "operating point" of a circuit.

In other words, for circuit simulation, and only speaking from my electronics experience:

- "Operating point" means the bias conditions

- "Working point" is ambiguous or undefined

It makes sense that a translator might translate them the same, even if they do not mean the same thing to an American, English speaking electrical engineer.

That's why I encourage Bordodynov to use "operating point" in the English description.? Months from now, if someone comes across his file, if the file's description says "working point" they might not know what it is.? If it says "operating point" they know what it is probably about.

Regards,

Andy

Re: LTspiceXVII crashing

#108491

I'm glad at least one or two other users see crashes.

I was kind of expecting a bigger avalanche.? ;)??? Really surprised by that.

But the phrase "The latest version of LTSpice XVII ( Oct 2018) seems better as I ran it ran almost all week with no crashes."? seems to indicate that a lot more crashes per week was the long accepted "normal" behavior.?? wow.?? (I wonder: accepted by many users?)

To rectify something I was probably not clear enough about: I've seen different versions of LTspiceXVII crash on all 4 PC's I tried it on over time, but currently 2 of those are no longer in use, and the recent version of LTspiceXVII (0ct 4), the one that crashes significantly less (but still a lot on some days) is only installed on 2 PC's: one at work and one at home.

The crashes are the "closes itself" type.? Whatever is causing them, one thing is very clear: it is something that occurs too often in LTspiceXVII, and never in LTspiceIV.?

Note again that the recent version only crashed while probing, this means after the simulation was already completed.? So in my case it seems to be related to the handling of GUI/mouse/keyboard user action or to updating the waveforms.? Schematics and simulator seem stable.? That's the impression I get in my case (the case rcjcarr reports? could be different).

The manifest file did not fix the upsampled look of LTspiceIV (also not after renaming as suggested).? It seems unwilling to use the available screen resolution (like a few other programs).? But its perfectly usable otherwise so I may still go back.? (I won't be needing spice in the coming weeks however)

Re: unable to import IGBT lib

#108488

Should have been in "  Temp" (That was the specific name of the file.) I uploaded it again just now and observed its existence.

Donald.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/&#92; <>

Show quoted text

On 14-Nov-2018 13:02, Andy ai.egrps@... [LTspice] wrote:
Donald wrote:
? ? "I uploaded IGBT_qtot1_error.zip with the relevant files"
Where?
Andy
---------------------------------------------------------------------------
Posted by: Andy <AI.egrps@...>
---------------------------------------------------------------------------

Re: LTspice model for capacitor start single phase motor

#108490

No one can determine to which file you are referring.? Where is it located and what is its name?

Is this for a hobby project or for your homework or project as a a university student or for a project where you work?

Are you just looking to see how the motor starts or perhaps you want to minimize peak starting current?

---In LTspice@..., <blueskyhua@...> wrote :

I find on ltspice one example for two phase motor. Can this be used to simulate a single phase motor?

any one one an example for 200w or so motor that can start with an capacitor?

thanks a lot!

lilyfish

Re: Problem with using LM4562

#108487

开云体育

OK, operating point is consistent with LTspice's nomenclature and most of available litterature..

Le 14/11/2018 à 18:29, Andy ai.egrps@... [LTspice] a écrit?:

Show quoted text

?

Jerry Lee Marcel wrote, "Can you elaborate on this difference (for us non-native)."

To me, from what I was taught in school and heard throughout my career, "operating point" is very specific and means the set of voltages and currents of the circuit, or the static bias conditions in the circuit.

"Working point" has no special meaning.? I guess it could mean anything.? I have never seen the expression "working point" used to mean the "operating point" of a circuit.

In other words, for circuit simulation, and only speaking from my electronics experience:

- "Operating point" means the bias conditions

- "Working point" is ambiguous or undefined

It makes sense that a translator might translate them the same, even if they do not mean the same thing to an American, English speaking electrical engineer.

That's why I encourage Bordodynov to use "operating point" in the English description.? Months from now, if someone comes across his file, if the file's description says "working point" they might not know what it is.? If it says "operating point" they know what it is probably about.

Regards,

Andy

Re: Behavioral source timestep limits ?

#108486

ericsson.sunshine asked about (I think) timestep effects, and Behavioral sources, and feedback.

I can't figure out what you are asking.??However, I guess the answer is to say yes, there can be limitations when adding anything to a simulation.? Everything interacts.? There might be more limitations when considering B-sources.

Regarding timestep and Bv/Bi sources, take a careful look at the tripdv and tripdt parameters of those functions.??The Help file description says little more than "Tripdv and tripdt control (time)step rejection."??There is a more complete explanation (although one that is almost as confusing) on the LTwiki webpage, here:

? ??

I have read that description a dozen times, but I still don't understand it.

Regarding feedback signals, you should be aware that the inputs to a B-source should not depend on instantaneous feedback from its own output.? This is mentioned on the Help page, this way:

? ? "However, it is assumed that the circuit element current is varying quasi-statically, that is, there is no instantaneous feedback between the current through the referenced device and the behavioral source output. Similarly, any ac component of such a device current is assumed to be zero in a small signal linear .AC analysis."

It is not clear exactly what that means.? It SEEMS to say that you shouldn't use a B-source anywhere near a feedback loop -- which seems like an extreme restriction.? On the other hand, the restriction stated above was given in the context of using pin currents as the inputs to the B-source, which would imply that maybe the restriction only applies to B-source formulas that use pin currents of the form Ib(Q1) or Id(M5), and not in general to all B-sources.? Regardless, I have come across mention of this restriction before, about instantaneous feedback and signals that vary faster than "quasi-statically" (meaning: they can only be DC or changing very slowly).

So I can't answer your question directly (because I don't understand the question).? But I can say this:

?- B-sources have some restrictions when used in feedback circuits;

?- B-sources have some restrictions even when not used in feedback circuits, regarding what signals can be used as their "inputs";

?- B-sources can have issues with timestep control;

?- B-sources have extra parameters to help remedy the problems with timestep control.

Regards,

Andy

Re: unable to import IGBT lib

#108485

Donald wrote:

? ? "I uploaded IGBT_qtot1_error.zip with the relevant files"

Where?

Andy

Re: unable to import IGBT lib

#108484

Going back to the original error (which is a different error and not fixed yet) ...

At the start of this thread, Anton's error message was "Unknown subcircuit...".? He found that the error went away when he pasted the contents of the .lib file into his schematic.

This tells us that the "Unknown subcircuit" error was not the first error Anton saw.? There was another error before this one, which was the real problem.? LTspice wasn't able to find his .lib file and include it.? So, what was wrong with the file he tried to include?? Chances are he had the wrong filename.

? ? .lib "lib adress"?

The "lib adress" part must be the exact name of the file, preferably not including the path, but it must have the right extension.? If the file that you downloaded was?TRENCHSTOP_H5_650V.lib, then your statement must look like this:

? ? .lib?TRENCHSTOP_H5_650V.lib

If the file you have is named?TRENCHSTOP_H5_650V.lib.txt because you opened it with a text editor and then saved it, then your statement must look like this:

? ? .lib TRENCHSTOP_H5_650V.lib.txt

Be careful because Windows likes to "hide extensions for known file types" and that will surely trip you up!? If your computer has that setting still enabled, disable it.? (For Windows 7, open Windows Explorer, go to Tools > Folder Options > View, and UN-check "Hide extensions for known file types".)

If the filename has a space in it, then it must be put in quotes:

? ? .lib "My new model file.txt"

Regards,

Andy

Re: Problem with using LM4562

#108483

Jerry Lee Marcel wrote, "Can you elaborate on this difference (for us non-native)."

To me, from what I was taught in school and heard throughout my career, "operating point" is very specific and means the set of voltages and currents of the circuit, or the static bias conditions in the circuit.

"Working point" has no special meaning.? I guess it could mean anything.? I have never seen the expression "working point" used to mean the "operating point" of a circuit.

In other words, for circuit simulation, and only speaking from my electronics experience:

- "Operating point" means the bias conditions

- "Working point" is ambiguous or undefined

It makes sense that a translator might translate them the same, even if they do not mean the same thing to an American, English speaking electrical engineer.

That's why I encourage Bordodynov to use "operating point" in the English description.? Months from now, if someone comes across his file, if the file's description says "working point" they might not know what it is.? If it says "operating point" they know what it is probably about.

Regards,

Andy

Re: Pspice lib to LTspice lib, IGBT-model

#108482

Anton,

There are also two other errors about "infinite recursion".? Those error messages are unbelievably long!? Whoever concocted this MOSFET model should be lined up against a wall and shot -- sorry everyone, I don't really mean that, it's only an expression -- but it is incredibly and unnecessarily complex.? Poorly made.? I was going to include those error messages here, until I realized they are so ginormous -- two lines of text spanning half a megabyte!? Ugh!

The fatal error message I got, was about qtot1(), not about qtot().

Did you run it under LTspice IV, or LTspice XVII?? I want to know if we are using the same simulator, because your error message was not the same as the one I have.

Regards,

Andy