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That's correct.

I'm still left wondering why only pi is defined for analysis. Of course, for "e", it's shorter to define it:

.param e exp(1)

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Maybe even a bit more explanation is necessary. To use the others in a simulation, it is necessary to include a directive, such as '.param k = 1.3806503e-23'. I hope that's right.

On 23/04/2025 11:00, Tony Casey via groups.io wrote:

On 23/04/2025 09:55, Александр Бордодынов via groups.io wrote:

I had to replace the parameter k with k0, because in Qspice k is the Boltzmann constant. At tau=10ns, the counting time was 2.2 seconds. And everything was fine.

k is also defined as Boltzmann's constant in LTspice.

I should clarify that:

k is pre-defined in LTspice, but only in the waveform viewer, not as a design parameter. Of the defined "constants" (e, pi, k and q) mentioned in the Help, only pi can be used as a design constant.

--
Regards,
Tony

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Thanks for your reply.
I'll connect the zener capacitors in anti-series...

Wouldn't it work correctly in anti-parallel?

Because both devices are just forward biassed diodes (as well). In anti-series, each diode blocks the other's forward voltage, so the total voltage "breakdown" in either direction is Vrev + Vfwd.

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Yes, they do behave like the 'avalanche' sort of 'zener', not the true Zener, and the mostly used TVS have a fairly high breakdown voltage, but also, almost all of them have a high maximum current rating. You can see by their physical construction, using a large die, that they are designed to dissipate power, even though it occurs over a very short time scale.

By high power, do you mean that TVSs behave like high voltage zeners when simulating?

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On 23/04/2025 09:55, Александр Бордодынов via groups.io wrote:

I had to replace the parameter k with k0, because in Qspice k is the Boltzmann constant. At tau=10ns, the counting time was 2.2 seconds. And everything was fine.

k is also defined as Boltzmann's constant in LTspice.

I should clarify that:

k is pre-defined in LTspice, but only in the waveform viewer, not as a design parameter. Of the defined "constants" (e, pi, k and q) mentioned in the Help, only pi can be used as a design constant.

--
Regards,
Tony

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I had to replace the parameter k with k0, because in Qspice k is the Boltzmann constant. At tau=10ns, the counting time was 2.2 seconds. And everything was fine.

k is also defined as Boltzmann's constant in LTspice.

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Input Offset Voltage, Input-Referred Noise, Regeneration Time, Power Consumption, Kickback Noise, Input Common-Mode Range, Supply Voltage. I need these parameters analysis in LTspice PLEASE HELP ME

You cannot hope to simulate things like offset voltage if you use ideal ideal models throughout - the devices will all be identical, i.e. zero offset. You also haven't specified any noise parameters in the model, so the simulated noise won't be realistic. The same thing applies to capacitances. First thing you need to do is get proper device models.

There's also an error in you schematic: Out- is shorted to Out+.

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Please don't put uploaded file directly in the Files location. They should be uploaded to Files > Temp, as the instructions say.

I have moved 456.asc to Temp.

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Actually, 'zener' embraces true Zeners , less than about 6V, and avalanche diodes, greater than about 6V.? LTspice models take account of this. TVS diodes are high-power avalanche diodes.

Good morning....
I'd like to know why LTspice simulates a TVS diode as a zener, even though its behavior isn't exactly the same.
I'd also like to know where I can find an LTspice library for some TVS diodes, for example, that are 15 volts and others that are around 140 volts, and that are bidirectional.

Thanks...for everything.

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I'd like to know why LTspice simulates a TVS diode as a zener, even though its behavior isn't exactly the same.
I'd also like to know where I can find an LTspice library for some TVS diodes, for example, that are 15 volts and others that are around 140 volts, and that are bidirectional.

Did you try looking on the sites of manufacturers that make TVS diodes, e.g. Diodes Inc., Littelfuse, Vishay etc?

You could always try looking on the group's Files section and put "TVS" in the search box in the top right. I got 24 hits, but not all them were relevant.

As far as LTspice simulations are concerned, actually unidirectional TVSs are similar to Zeners, but tend to higher current. Bidirectional ones are equivalent to two unidirectional ones in anti-series.

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I am trying to build a model for MJ11021 to be used in an AB amplifier simulation.? Link to .

I made an attempt in building a model for the part PNP type first.? I also created a simulation to validate against the datasheet.

Validation part 1: DC simulation to Verify hFE and VCE.??

Never got past part 1!?

Part 2: Transient simulation? to measure switching time.

?

I have uploaded the files to temp directory under /g/LTspice/files/Temp/MJ11021.zip

?

It is not working and I am having a hard time figuring out how to fix the parameters in order to get it validated.? Any help and guidance in how to proceed to fix/tune the model parameters and how to setup the simulation to validate the model against key datasheet specs. would be greatly appreciated.

Developing a SPICE model for a Darlington is a considerable undertaking. Unfortunately, the Onsemi datasheet is not quite comprehensive enough to derive an accurate one.

The good news is that although Onsemi don't provide SPICE models for either of these devices, it does for the similar MJH11021 and MJH11022 transistors. These will be the same die, but in TO-247 packages instead of TO-3. Perhaps you were unaware of these modern equivalents?




You should nevertheless validate these models, at least partially. I recommend you construct several testjigs to re-generate the the graphs in the datasheet. Unfortunately, graphs for the output characteristic and FT are not shown, but you should check:

1. Switching Time (Figure 2)
2. The "On" Voltage (Figure 8 in the MJH11021/22 datasheet
3. Figure 6 - DC Current Gain
4. Figure 7 - Collector Saturation Region

--
Regards,
Tony

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We can't help much unless you let us see more of what you are doing. Upload your .ASC file AND all the other files required to run the simulation, but not .RAW? and .LOG files or pictures,? in a ZIP archive to Files => Temp.

Go to the web page: /g/LTspice/topics. Click on Files in the list on the left. Then click on Temp. Then click on New Upload in the blue box at top left. Click on Upload File in the drop-down menu. Then send a message to tell us that you did that.

Hello guys. Please help my Thesis. I want to make Comparators design of sar adc i have built Comparator in LTspice i wanna analysis. But i cant PLEASE HELP ME OUT