Re: How to measure efficiency over specific time interval
On 03/04/2024 23:47, sam@... wrote:
I'm having
trouble getting my efficiency measurement to work in?LTC3129
simulation.zip.
It simulates the start-up of a DC-DC converter, which charges an
output capacitance.
I want to measure the efficiency as ECapMax/Ein, which is the
energy in the output capacitance C8&C9 when they're "fully
charged" divided by the energy sourced from the input source V2
over this time interval.
I have the measurements of ECapMax and Ein working separately, but
the efficiency evaluates as 0.007, the ending time of the
transient simulation.
Can someone help me fix my .meas statements, please?
Note: Efficiency should evaluate to approximately 36% in this
simulation.
There is a syntax error in your ".meas efficiency.." statement. You
need a "param" keyword, i.e.:
.meas efficiency param ECapMax/Ein
When you do that, you get an answer of 35%. Whether that's actually
correct or not, I can't say. Your approach is obscure and not how I
would have chosen to do it. Normally, to get a reliable figure for
efficiency in switching circuits, it is necessary to integrate over
an integral number of switching cycles. It seems rather unlikely
that you would only achieve 35% in a switching converter, but then
you do have an input series resistor of 24.9Ω. Your input source
supplies a total of 202.82?J, of which 57.529?J is lost in this
resistor. But then, I have no idea what you're doing, so can't
comment further.
--
Regards,
Tony
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Re: question concerning the displayed breakdown voltage of zener diode MMBZ6V8ALY
The name "Zener" is only technically correct for a diode with a breakdown of approx. 5 volts and less. Above 5 volts, the diodes are actually "Avalanche" Diodes. For whatever reason Zener has stuck.
Zener diodes have "rounded" knee while Avalanche diodes have a "sharp" knee. Avalanche diodes are much nosier than Zener diodes especially operating near the knee.
Noise diodes are Avalanche diodes.
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How to measure efficiency over specific time interval
Hi, I'm having trouble getting my efficiency measurement to work in? LTC3129 simulation.zip. It simulates the start-up of a DC-DC converter, which charges an output capacitance. I want to measure the efficiency as ECapMax/Ein, which is the energy in the output capacitance C8&C9 when they're "fully charged" divided by the energy sourced from the input source V2 over this time interval. I have the measurements of ECapMax and Ein working separately, but the efficiency evaluates as 0.007, the ending time of the transient simulation. Can someone help me fix my .meas statements, please? Note: Efficiency should evaluate to approximately 36% in this simulation.
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Re: How to simulate the gate charge characteristic given in the datasheet of a mosfet?
On Thu, Apr 27, 2023 at 09:03 AM, <cornel_bejan15@...> wrote:
Do you know if exists any ltspice simulation file example for this thing on how to do correctly?
I have uploaded a simple test circuit to show how the gate charge curve can be obtained at mosfet gate charge. I used the 2N7002 so you will need to replace that with your mosfet and adjust V1 and I1 to match the test condition drain voltage and current from the datasheet. In the plot file the x-axis is set to Igate*time and displays in Amp-seconds (As) which is equal to Coulombs (C). You may need to adjust the gate current and/or the simulation time to reasonable values for your mosfet.
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Re: It is possible to use .fra to analyze a filter, low pass for example
Big error in my advice. .AC rather than .frequency.
Sorry
Jim
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Carlos asked for an example showing how to simulate and plot the Bode plot from a linear low-pass filter in LTspice. I realize everyone needs to start from the beginning, but it is surprising if you could not find a thousand examples already. But I uploaded an example simulation for you.? It is here: ? ? Files > Temp > Low-pass_example.asc ? ? /g/LTspice/files/Temp/Low-pass_example.ascClick on the link above to download it.? Or, go to the group's webpage, click "Files" in the menu on the left, then click "Temp" to go to the "Temp" subdirectory or folder, and you will find the file in that folder. To use it, open it in LTspice and click "Run".? When it is done (it should take less than a tenth of a second), click on the wire with the "Out" label, and you will see the Bode plot of the filter. An ".AC" analysis is the simplest kind to see Bode plots of linear filters. Read LTspice's Help, which comes with the program. LTspice comes with several example schematics in the folder "examples\Educational".? Many are .TRAN analyses but several are .AC and make Bode plots, without using ".FRA". Andy
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Re: I made a script to plot .meas data in 3d against 2 step'd parameters
I never saw a python script that I didn't like!? ?:-) But to get yours to run I had to change line 64? and comment out line 69. So there's something about how you wanted to pick files that's confusing.? But with this I was able to plot the example file and I find it very susefule to have.?? tnx, Tim
? ? if len(listlogfiles)==1: logfile = listlogfiles[0]
? ? else:
? ? ? ? print('\nwhich log file?')
? ? ? ? for n in range(len(listlogfiles)):
? ? ? ? ? ? print(' ? {}:{}'.format(n,listlogfiles[n]))
# ? ?logfile = listlogfiles[int(input())]
?
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Re: It is possible to use .fra to analyze a filter, low pass for example
Carlos asked for an example showing how to simulate and plot the Bode plot from a linear low-pass filter in LTspice. I realize everyone needs to start from the beginning, but it is surprising if you could not find a thousand examples already. But I uploaded an example simulation for you.? It is here: ? ? Files > Temp > Low-pass_example.asc ? ? /g/LTspice/files/Temp/Low-pass_example.ascClick on the link above to download it.? Or, go to the group's webpage, click "Files" in the menu on the left, then click "Temp" to go to the "Temp" subdirectory or folder, and you will find the file in that folder. To use it, open it in LTspice and click "Run".? When it is done (it should take less than a tenth of a second), click on the wire with the "Out" label, and you will see the Bode plot of the filter. An ".AC" analysis is the simplest kind to see Bode plots of linear filters. Read LTspice's Help, which comes with the program. LTspice comes with several example schematics in the folder "examples\Educational".? Many are .TRAN analyses but several are .AC and make Bode plots, without using ".FRA". Andy
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I made a script to plot .meas data in 3d against 2 step'd parameters
I was having trouble in a linear psu lab trying to predict what components to use for a particular load resistance, current, ripple, ect. and wanted a better visual of how various parameters affected those, but to change the abscissa I would have to switch the order of the stepped parameters and re-simulate it each time and try to decipher the overlapping plots of the other steps.? so I made a script to plot both using matplotlib in python
https://github.com/Sean-no-soup/LTspice-log-plotter/tree/main
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Re: It is possible to use .fra to analyze a filter, low pass for example
On 03/04/2024 06:19, Carlos Delfino wrote:
I'm
reading about the existence of the .fra component that generates a
"Bode" diagram for an SMPS. Would it be possible to use this same
component to analyze some type of filter, a low pass for example?
Unless your filter is non-linear, it is easier and orders of
magnitude quicker to simply use .AC analysis. With this, you can
also directly plot return loss and complex impedance by adding a
.NET directive.
Regards,
Tony
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Re: It is possible to use .fra to analyze a filter, low pass for example
Look up in the Help for directives. I think it is .frequency ?(word “frequency” preceded by a period or dot)
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As I'm learning how to use LTSpice, could you send me an example or an article I can read on how to do it?
Em qua., 3 de abr. de 2024 às 03:24, Jim Wagner < wagnejam99@...> escreveu: Should have added “continuous” (e.g. not time-varying) as one of the criteria.? This is the one that SMPS usually violates and needs special techniques ro analyze.
Jim
spice already does that for frequency dependent linear networks. You do not need any special components.
Jim Wagner
I'm reading about the existence of the .fra component that generates a "Bode" diagram for an SMPS. Would it be possible to use this same component to analyze some type of filter, a low pass for example?
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Re: It is possible to use .fra to analyze a filter, low pass for example
As I'm learning how to use LTSpice, could you send me an example or an article I can read on how to do it?
Em qua., 3 de abr. de 2024 às 03:24, Jim Wagner < wagnejam99@...> escreveu:
Should have added “continuous” (e.g. not time-varying) as one of the criteria.? This is the one that SMPS usually violates and needs special techniques ro analyze.
Jim
spice already does that for frequency dependent linear networks. You do not need any special components.
Jim Wagner
I'm reading about the existence of the .fra component that generates a "Bode" diagram for an SMPS. Would it be possible to use this same component to analyze some type of filter, a low pass for example?
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Re: It is possible to use .fra to analyze a filter, low pass for example
Should have added “continuous” (e.g. not time-varying) as one of the criteria. ?This is the one that SMPS usually violates and needs special techniques ro analyze.
toggle quoted message
Show quoted text
spice already does that for frequency dependent linear networks. You do not need any special components.
Jim Wagner
I'm reading about the existence of the .fra component that generates a "Bode" diagram for an SMPS. Would it be possible to use this same component to analyze some type of filter, a low pass for example?
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Re: It is possible to use .fra to analyze a filter, low pass for example
spice already does that for frequency dependent linear networks. You do not need any special components.
toggle quoted message
Show quoted text
I'm reading about the existence of the .fra component that generates a "Bode" diagram for an SMPS. Would it be possible to use this same component to analyze some type of filter, a low pass for example?
|
It is possible to use .fra to analyze a filter, low pass for example
I'm reading about the existence of the .fra component that generates a "Bode" diagram for an SMPS. Would it be possible to use this same component to analyze some type of filter, a low pass for example?
|
Re: How to simulate the gate charge characteristic given in the datasheet of a mosfet?
Abby asked, "Could you kindly explain why the linearly increasing gate voltage method was used instead of the constant gate current method for the gate charge simulation?"
I am not Tony.? But if you apply a linearly increasing gate voltage, then it has a constant dv/dt.? Doing that while monitoring the current into the gate is another way to measure capacitance, while it changes versus DC voltage.
Andy
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I will close this interesting discussion. The initial goal was to reduce simulation time; my mistake, using "Marching Waves".I tried to reduce the burst frequency (150MHz to ~13MHz), without success; tried to save data after a delay; without success.I'm going to return to my first "solution": Split the diagram, adapt the I/O as best as possible and simulate each part separately; in my humble opinion, the only acceptable solution in my case, not having the possibility of acquiring a faster PC...Many thanks to everyone for your help and excellent information. Best regards, Rudi
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Re: LTspice icons too small
It's the hammer symbol on the toolbar.
On 2024-04-01 21:45, Epignathus wrote:
I’m
running LTspice XVII(x64) (17.0.37.0) and I don’t see a
“Settings”. Am I blind, or is there a trick to making this
user directive appear?
Thanks,
Doug
Ronald
?
?
There
is a setting to change that. Settings => Schematic tab
=> Pen thickness. The setting is remembered.
On
2024-03-27 13:44, Andrew Lohmann wrote:
I've always
found the lines, such as wires, to be thin, so difficult
to see.
--
OOO
- Own Opinions Only
Best wishes
John Woodgate, Rayleigh, Essex UK
Keep trying
--
OOO - Own Opinions Only
Best wishes
John Woodgate, Rayleigh, Essex
UK
Keep trying
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Re: LTspice icons too small
Thank you – I’ve upgraded to 24.0.7 and of course I see Settings… ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Andy I
Sent: Monday, April 1, 2024 13:51
To: [email protected]
Subject: Re: [LTspice] LTspice icons too small ? In versions 17.*, it is called the Control Panel.
But its arrangement has changed, and you won't find the same settings in the same places in v17.* as in v24.*.? The wire thickness setting is in:
? ? Control Panel > Drafting Options tab > Pen thickness.
Andy
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Re: LTspice icons too small
In versions 17.*, it is called the Control Panel.
But its arrangement has changed, and you won't find the same settings in the same places in v17.* as in v24.*.? The wire thickness setting is in:
? ? Control Panel > Drafting Options tab > Pen thickness.
Andy
|
Re: LTspice icons too small
I’m running LTspice XVII(x64) (17.0.37.0) and I don’t see a “Settings”. Am I blind, or is there a trick to making this user directive appear? Thanks, Doug Ronald ?
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From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate
Sent: Wednesday, March 27, 2024 07:34
To: [email protected]
Subject: Re: [LTspice] LTSpice icons too small? There is a setting to change that. Settings => Schematic tab => Pen thickness. The setting is remembered. On 2024-03-27 13:44, Andrew Lohmann wrote: I've always found the lines, such as wires, to be thin, so difficult to see.
--
OOO - Own Opinions Only
Best wishes
John Woodgate, Rayleigh, Essex UK
Keep trying
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Tony Casey
Tim Hutcheson
John Woodgate