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Re: Hello! I want to include/understand the operation of a switch made up of a P_MOS and a N_MOS in parallels and how to assemble them to convert an analogical signal into a numerical signal.Help!

 

And your LTspice-related question is what?

Regards,
Tony
Re: high frequency MHz and GHz range BJTtransistor or Mosfet

 

Hello?Shikha,

NXP has a lot of RF-transistors and they provide SPICE models as far as I remember. Others like Onsemi and Infineon have RF-transistors too.

Best regards,
Helmut
Re: Current Dependent Voltage Source

 

"
?
rmoreno.phone" asked how to enter a table of measured values for her/his CCVS.

Vlad might have had the table descriptions a little bit confused with respect to your question, because I think the data you have is voltage/current values, not voltage/time values.? You wanted a controlled or dependent source, not an independent source.

Using SPICE's built-in H element (current controlled voltage source or CCVS), LTspice *MIGHT* have the ability to accept a table of current/voltage values.? See the Help pages for E (VCVS) and G (VCCS) elements.? A table is listed as an option. ?"A look-up table is used to specify the transfer function." ?The same 'table' description is not listed for the F (CCCS) and H (CCVS) elements.? I am not sure if that was an omission on those Help pages, or if that option really doesn't exist for those two controlled sources.? The "LTwiki" () is where I usually go when I have questions about the Help pages.? Unfortunately, the LTwiki also doesn't show a table option for the CCVS.? That leads me to believe that you can't use a table with the standard CCVS element.

But LTspice's B-elements can do that and much more.

Here is from the Help page for B-elements:

? table(x,a,b,c,d,...) ??Interpolate a value for x based on a look up table given as a set of pairs of points.

Start with a Bv symbol, then right-click on "V=F(...)" and edit it.? I think (but could be wrong) it should look like this when you are done:

V=Table( I(V4), 0mA, 0V, 1mA, 1mV, 2mA, 1.9mV, 3mA, 2.5mV ...)

where I(V4) means the current measured through V4 (this is your controlling current), and the pairs that come next, are the (current, voltage) pairs that you measured.

I have rarely used the Table() functions in LTspice, so please excuse my inexperience with them.

Regards,
Andy
Re: high frequency MHz and GHz range BJTtransistor or Mosfet

Frank Mead
 

2n2857, 2n3866, AT 41485, HXTR5105...good luck...
Frank

On Wed, Aug 3, 2016 at 11:58 AM, shikha khurana shikhakhurana10@... [LTspice] <LTspice@...> wrote:
?

Dear all,

Can any one suggest me high frequency BJT Transistor or MOSFET available for
working with LTspice.
Thanks
Regards
Shikha
high frequency MHz and GHz range BJTtransistor or Mosfet

 

Dear all,
Can any one suggest me high frequency BJT Transistor or MOSFET available for
working with LTspice.
Thanks
Regards
Shikha
Re: Sub circuit heat dissipation not showing

 

Hello Brad,

Not at my computer right now so I can't check, but maybe you just need to go to the control panel and enable save (subcircuit) currents.
LT1171 model: syncronization not working

 

I am trying to make a negative buck regulator with LT1171, based on the circuit given on page 13 of the LT1170/71/72 datasheet. I am trying to add clock syncronization as shown on page 11 of the same datasheet (the FET-controlled version, for now)

According to the datasheet:

>?Synchronizing occurs when the VC pin is pulled to ground
> with an external transistor. To avoid disturbing the DC
> characteristics of the internal error amplifier, the width of
> the synchronizing pulse should be under 0.3¦Ìs.?
> ...
>?The transistor?must be capable of pulling the VC pin to within 200mV of
> ground to ensure synchronizing.

When I model this circuit in LTSpice, I find that although I pull VC ?below GND (the same potential as the LT1171 GND pin, actually at -18 V in this circuit) with repetition frequency 138 kHz and 0.1 us pulse width, the switching current doesn't synchronize with this signal.

I've uploaded my ASC file to the Temp directory as Neg Buck 20160803.zip.
?
If anyone has experience with this part, can you tell me,

* Does the LT1171 spice model include the synchronization feature?
* Or am I just doing something wrong?

Side question:

* Can anyone recommend a surface mount equivalent to the VN2222 FET recommended in the datasheet circuit? And is an LTSpice model available? (it seems that capacitive shoot through from the control signal to the VC pin can be an issue when using a poorly chosen FET here)

Thanks!

(For the search engines: this question might also be interesting to people working with LT1070, LT1071, LT1072, LT1170, or LT1172)
I want to know

[email protected]
 

Hello! I want to understand the operation of a switch made up of a P_MOS and a N_MOS in parallels and how to assemble them to convert an analogical signal into a numerical signal.Help!
Hello! I want to include/understand the operation of a switch made up of a P_MOS and a N_MOS in parallels and how to assemble them to convert an analogical signal into a numerical signal.Help!

[email protected]
 

Write a message...
BS250 & BS170 SIM

 

they look like they should work, but the don't, how can I add them to my CMP folder, that is what is the correct model layout.

Thanks

Jeff
Re: Sub circuit heat dissipation not showing

John Woodgate
 

¿ªÔÆÌåÓý

Repeat your question. That saves anyone thinking of answering having to search for it.

?

With best wishes DESIGN IT IN! OOO ¨C Own Opinions Only

J M Woodgate and Associates Rayleigh England

?

Sylvae in aeternum manent.

?

From: LTspice@... [mailto:LTspice@...]
Sent: Wednesday, August 3, 2016 4:21 PM
To: LTspice@...
Subject: [LTspice] Re: Sub circuit heat dissipation not showing

?

?

Hi .. No one has a reply to my question? Thanks Brad
Re: Sub circuit heat dissipation not showing

 

Hi .. No one has a reply to my question? Thanks Brad
Need spice model for IR TX and RX

[email protected]
 

Hi Team,


?????????????? I need spice model for TSMF1020 and TEMD 1020 IR?TX and RX part.




Regards,

Dhanabal T

?????????
Re: Mechanical switch

 

Yahoo! strongly brakes. I did half an hour as the update file and cover letter, and they still do not.
See?bounce.zip in temp folder.

Bordodynov.
?
Re: Mechanical switch

 

Go to Text editor file?bounce.asc.
Replace?.lib ..\sym\Source\source.lib to?.lib source.lib
I am sorry.

Bordodynov.
?
Re: Mechanical switch

 

Hi.
In a packed folder contains files:
bounce.asc
source.lib
bounce.asy
bounce.plt

I rechecked all the (symbol). But netlist showed not the correct link to the library. I was surprised and delete the symbol, and then put it in place. I restarted the file.
See file bounce.zip (update) in temp folder.
I am sorry.

Bordodynov.


03.08.2016, 13:50, "ericsson.sunshine@... [LTspice]" <ltspice@...>:

Hi,?Bordodynov:

.lib ..&#92;sym&#92;Source&#92;source.lib

in the file, It can't find this.

Thank you for the file

Best regards.
Re: Modelling an optoisolator

 

skipcave wrote:
"I have a requirement to model an optoisolator in LTSpice."

Call me old fashioned, but why don't you start with one of the models in the group's Files section? Use "opto" as a search term and you'll get quite a few hits.

Regards,
Tony
Re: Need help to design a transimpedance amplifier

[email protected]
 

Thanks Jim Wagner...

This is what the mistake we made in our previous design...
We had just gone with simulation results and at last got a very noisy amplifier.
Re: Mechanical switch

 

Hi,?Bordodynov:

.lib ..\sym\Source\source.lib

in the file, It can't find this.

Thank you for the file

Best regards.
Re: Mechanical switch

 

Hi, :

I found a article talking about the breakdown voltage when arcing happens.
At here:
(of course, I am not good at this, it's just discussed. Not sure what's the exact correct answer.)

From the article, it says through the Paschen's law, it could decide the breakdown voltage depends on the distance & gas pressure.It's not linearity.
So under some certain situation (fixed pressure, distance), in the instantaneous time point of the switch on -> off, the contact point where arcing happens should be the most tendency point referring to the "Paschen curve" where pd product is the value at which the breakdown voltage is the lowest.
So the breakdown voltage is able to be estimated, the current flowing through the inductor should be continuous ,supposed it's Ipeak, the instantaneous energy stored in the inductor is 1/2*L*Ipeak^2, and this energy should dissipated through the arcing time, which it's supposed to be V(t)*I(t)*dt (V(0)=breakdown voltage, I(0)=Ipeak, t=0 when arcing happens). Otherwise, maybe there is another path which also consumes the energy.

Just for simple reference.
Appreciate for any opinion to discuss this, so far , I can't find any further article which talking about this on internet.
(But I really like to know more about this.)

Best regards.

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