I just went to diodes.com and found the newest spice model for the

Then start with the simplest circuit of a single stage, then add stages until it disproves the conjecture.

Tim

On Thu, Jul 6, 2023 at 04:33 AM, Tim Hutcheson wrote:

I got the impression that the switching mechanism is essentially the same as he describes in a 2008 lecture on SCC, at ?where at about 55 minutes into the slides hew states just that.? So then I looked at the schematic in one of his students thesis for a small implementation and it seemed to confirm this.? I could be wrong.

IMO, you are wrong, Tim. The video is about a quasi-continuously varable step-down DC/DC converter.

Concerning his self-adjusting autonomous 4s battery equalizer, Sam Ben-Yaakov described a natural self-balancing behaviour (propagation indeed) permitting the use of 2 switches per cell in case it is acceptable that the 4s cells series-arrangement balancing takes 5 hours.?An LTspice simulation could validate this. Can an LTspice simulation show that a 104s arrangement behaves the same natural way?

It's quite sinple. One must to concentrate on




Regards,
Steph

On Thu, Jul 6, 2023 at 02:22 AM, Lohi Karhu wrote:

Funny thing is, that I filed a patent, way back in about 2007 on balancing ‘energy storage devices’ using a switched-capacitor mechanism…
US 7,994,756 B2

Nokia Corporation, unfortunately no series layout.

Richard wrote, "The files are dated, use the most recent one."

That's one way of thinking about it, but probably not the best.? Newer does not mean better.? You might get the one made by someone who just got out of high school and first used SPICE two weeks ago.??You could also base your decision on who made the model, or what company published it (may or may not be the same).? Preferably, you should try the models and compare them with datasheets, or with measurements of real parts.

Andy

The files are dated, use the most recent one.

vedhaanth648,

I uploaded your file for you.? It is in the Temp folder.? BSS138.zip.

To answer your question "i dont know which one to use", use whichever one you want to use.? All three of them appear to be SPICE models, so any of them should work in SPICE (and LTspice).? Take your pick.??They appear to be MOSFET models.? Two of them can be used directly.? But one of them (BSS138.lib) is a special model that has a fourth pin for temperature.? To use that one, you will need to create (or borrow) a special MOSFET symbol that has the fourth pin, and then use that pin correctly.? That might mean connecting the fourth pin to a voltage source, or to an RC network to represent a heatsink.

So I recommend starting with the other two models first.

The other two models are ordinary 3-terminal subcircuits.? You can use them with LTspice's normal MOSFET symbols (either NMOS or PMOS as appropriate).? After adding the symbol to your schematic, then use Ctrl-right-click on the symbol, and change the Prefix value to "X" (without the quotes), and click OK.

Andy

Please do not point us to some random website that has your files, even if it is your own.? UPLOAD your files to our group's Files section, into the "Temp" folder:

? ??/g/LTspice/files/Temp

Maybe you forgot to read what it says on the group's main webpage: "do not point us to other ("third party") file storage websites".? Go back now and read the group's main webpage.

Andy

开云体育

Please DO NOT send us to third-party sites for data. Upload your .ZIP to Files => Temp, and then tell us you did that. Meanwhile, you mean BSS138, not BS138.? The way to add third-party models is explained in the Help, but it's best to put the model file in the same folder as the .ASC. Don't try to add it to LTspice's native files, which is not straightforward and often leads to problems.

i have the following 3 files related to it.

i dont know which one to use

and which standard component to use in place of this component

OTOH, we don't even need a calculator to compute the MTTF of such a circuit.

-marcel

Tim wrote, "Yikes, my calculator says that's more than? 2.028e31 switches."

That could be a challenge even in LTspice.

At the end of the day, subcircuits don't make simulations smaller.? If there are 2.028e31 switch subcircuits, they are not represented by one subcircuit that gets 'called' 2.028e31 times.? They have to be expanded into 2.028e31 equivalent circuits that become part of the full netlist.? That's a lot of transistors and more.

I don't think today's PCs are quite capable of that.? ;-)

Andy

I got the impression that the switching mechanism is essentially the same as he describes in a 2008 lecture on SCC, at ?where at about 55 minutes into the slides hew states just that.? So then I looked at the schematic in one of his students thesis for a small implementation and it seemed to confirm this.? I could be wrong.

Tim

开云体育

On 06/07/2023 11:02, garvind25@... wrote:

Pls read the value of Cox as 8.5fF/um^2. It is the oxide capacitance per unit area. While implementing the formula fT = gm/2*3.14*W*L*Cox, W and L are MOSFET sizes in um.

?

The y-axis is in ohm-1 (ohm inverse or siemens). This is the unit of gm. In other words, while implementing the above fT formula, the y-axis is taking the units of gm only. It should be of frequency (in Hz or KHz etc)

In the Files section of the group's archives, there is a demo schematic that shows how to plot Ft vs. Id. Once you understand how it works, you can adapt it to .MEASure gm as well as Ft, then you can also plot Ft vs. gm.

Funny thing is, that I filed a patent, way back in about 2007 on balancing ‘energy storage devices’ using a switched-capacitor mechanism…
US 7,994,756 B2

have a fine day, all…

Barry Rowland
Just a simple ?? guy in ??...

开云体育

On 06/07/2023 10:54, Tony Casey wrote:

In .AC plots, Freq(uency) and Omega are also recognised.

I forgot: in .TRAN plots, "time" is also recognised. See:

Help ?? LTspice XVII ?? Waveform Viewer ?? Waveform Arithmetic

..for definitive information.

Thanks for the quick reply. Pls find below the answers to your queries:

?

Pls read the value of Cox as 8.5fF/um^2. It is the oxide capacitance per unit area. While implementing the formula fT = gm/2*3.14*W*L*Cox, W and L are MOSFET sizes in um.

?

The y-axis is in ohm-1 (ohm inverse or siemens). This is the unit of gm. In other words, while implementing the above fT formula, the y-axis is taking the units of gm only. It should be of frequency (in Hz or KHz etc)

?

Thanks again,

Arvind Gupta

?

On 06/07/2023 09:13, garvind25@... wrote:

I am trying to plot a few graphs in LTSPICE XVII and have a couple of queries. Hope someone will answer:

?

** Can I define a constant capacitance value in LTSPICE such as Cox = 8.5fF/u^2 so that after simulation, I can manipulate the graph to plot expressions like fT = gm/2*3.14*W*L*Cox? If I simply use the magnitude of Cox as 8.5f in Expression Editor, though I get the graph, the unit of the Y-axis isn’t frequency (as it should be). I event tried by saving the value in “plot.defs” file. I am still getting the same graph with the unit on Y axis as something else. Basically, the Farad quantity is getting neglected and only the numerical value is getting used. ?The x-axis is a voltage source (swept by a dc sweep command).



** As I know, after the simulation, I can manipulate the graph to plot expressions on the y-axis (such as for fT as in above query). Is it possible to plot a graph with expressions on both Y axis and X axis? For eg. how to plot a graph of fT vs gm/Id (where the fT expression will be on y axis and ‘gm/Id’ expression on x axis).

As a general rule, expressions in the waveform window can only comprise waveforms that are available in the "Add Traces to Plot" dialogue and constants. However, there are exceptions:

1. In .AC plots, Freq(uency) and Omega are also recognised.
2. Some other "constants" are also available for use in expressions: "k" or "K" is Boltzmann's constant and "q" or "Q", the elementary charge, pi, and "e" or "E" (2.7182..).
3. "K" is always recognised as Boltzmann's constant, unless it is immediately preceded by an number, when it reverts to 1000x. Ditto "E", when used as, e.g. 1E-6. All other range multipliers up to "T" (1E12) and down to "f" (1E-15) are unambiguous. There is no case distinction.
4. .Parameters defined in the schematic are normally not recognised, unless they are stepped, then they are available for use in expressions. It is not necessary to use braces, {}.
5. The only units that are accepted in expressions are V, A and s. But LTspice provides "derived" units in axes annotations, if it can work out what they should be. Whether that's a benefit or cause for confusion is an open question. So, normally, LTspice can easily work out annotations of V, A, W and ?. Siemens (or mhos) are denoted as ?^-1, but I guess it could have used the symbol, ?. Other units it might not present succinctly.

If you want to plot or use gm, then remember it is dI/dV, so you can use the d() operator.

?

Is it possible to plot a graph with expressions on both Y axis and X axis?

?

Did you try it? Depending on the analysis mode, expressions can be used for both axes. .AC plots can only use Frequency for the X-axis. It's not hard to work out why.

Except for plotting expressions, units are generally ignored in LTspice. So remember, 1F is the same as 1fF. When a range multiplier is encountered, it also acts as a delimiter, ignoring everything non-numeric that follows. So, 3k3=3300, but 1A=1V=1.

Certain things saved in plot.defs are very useful in plot expressions, but since customisation of plot.defs in kind of encouraged, it is inherently non-portable. So, for example, I have a function: dB(x)=20.log10(x), which makes trace titles much neater, but will cause an error for anyone else that does not have this function defined.

Nothing added to plot.defs will work until LTspice is closed down and re-started.

开云体育

What you want to do can be done. Note the following:

1. In the Cox formula, LTspice stops parsing after the 'f'. What is 'u' anyway? Is it a fixed voltage?
2. You say that the y-axis unit isn't frequency, but you don't help us by saying what it is. If it is volts, divide the formula by (1V*1s).
   
3. You often have to divide a node voltage or current (which is what can be plotted) by '1 unit' to get the y-axis unit correct. For example, if you apply a 1 A current generator to a node and plot the node voltage, to get the y-axis to be 'ohms', you plot 'Vnode/1A'.
   
4. You can plot an expression on the x-axis, unless you have done an AC sweep. Right-click on it and you get a pane in which you can type the variable you want to plot. For example, you can enter 'V(in)' to use the input voltage as the x-axis. With an AC sweep, you can only have frequency as the x-axis.
   

Hi,

?

? I am trying to plot a few graphs in LTSPICE XVII and have a couple of queries. Hope someone will answer:

?

** Can I define a constant capacitance value in LTSPICE such as Cox = 8.5fF/u^2 so that after simulation, I can manipulate the graph to plot expressions like fT = gm/2*3.14*W*L*Cox? If I simply use the magnitude of Cox as 8.5f in Expression Editor, though I get the graph, the unit of the Y-axis isn’t frequency (as it should be). I event tried by saving the value in “plot.defs” file. I am still getting the same graph with the unit on Y axis as something else. Basically, the Farad quantity is getting neglected and only the numerical value is getting used. ?The x-axis is a voltage source (swept by a dc sweep command).



** As I know, after the simulation, I can manipulate the graph to plot expressions on the y-axis (such as for fT as in above query). Is it possible to plot a graph with expressions on both Y axis and X axis? For eg. how to plot a graph of fT vs gm/Id (where the fT expression will be on y axis and ‘gm/Id’ expression on x axis).

?

Looking towards your pointers.

?

Thanks and regards,

Arvind Gupta