Re: AD630 circuit simulation, no line shown
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LT1171 model and synchronization function
Hi,
Is anyone experienced with the LT1171 and LTSpice.
Is the synchronization function implemented in the model?
I am trying to make a negative buck regulator based on the circuit in the datasheet, but with external clock synchronization (also based on the LT1171 datasheet, page 11). I put my circuit in the Files->Temp folder as Neg Buck 20160803.ZIP. I don't see the switching current synchronizing with my low pulses on the VC pin.
I also tried adding synchronization to the postive boost circuit provided in the LTSpice jigs folder, and got similar results.
Thanks
Matt
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
? ?"What is your definition of high frequency? For some people, it is 1MHz, for others it might be 10GHz."
By definition, high frequency means 3 MHz to 30 MHz.
Even saying "GHz range" -- does that mean 1 GHz, or 700 GHz?
You gotta love those vague questions....
Andy
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Re: AD630 circuit simulation, no line shown
tob.nagel?wrote:
? ?"simple task: I want to simulate the circuit in the following picture:"
Please don't send links to off-site file storage areas.
Some of them are like computer viruses.? They take forever to load, and some of those sites start downloading crap to your computer without you clicking anything.? Some of them have so many links to places that actually have computer viruses, that they are dangerous places to go to even if you try to be careful.
Even when those sites are not unsafe, there is no need to direct us to off-site storage areas.
This group you are in has a File storage and a Photo storage area.? Use them.
? ?"Therefore I created this in LTspice:"
Never send photos of your LTspice schematics!? It is not useful when someone does that.
UPLOAD your schematic (the .ASC file, and all models and other things it depends on) to the group's Temp folder:
When you are inconsiderate enough to upload just a photograph or screen capture of your LTspice schematic, you force all of us to re-enter your schematic all over again.? You also deny us from knowing what attributes are attached to your components.? That's why this isn't helpful.
Please, go back and READ and RE-READ the email you received when you joined the group.? Also read the main webpage for the group.? Then try to follow the instructions contained in them.
Andy
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AD630 circuit simulation, no line shown
Hey, simple task: I want to simulate the circuit in the following picture: https://s31.postimg.org/cfx03t823/circuit.pngTherefore I created this in LTspice: https://s32.postimg.org/z7tgiq65x/schematic.png ? But when I hit the simulate-button, sometimes it only works with 1ns per second and sometimes it's pretty fast without me changing anything. Additionally there isn't any line in the diagram when i choose the fitting trace. If I remove the right op amplifier (AD630), the rest works fine, so I assume that the problem is here. I used the netlist provided from | | | | The AD630 is a high precision balanced modulator/demodulatorthat combines a flexible commutating architecture with theaccuracy and temperature stability af | | | | Preview by Yahoo | | | ?
Can anyone see my mistake? I've spent many hours for searching now...
Thanks!
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
Try a 2N918. Small signal, but I think it is in the built-in LTspice library.
Jim
James Wagner Oregon Research Electronics
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Shikha wrote:
"Can any one suggest me high frequency BJT Transistor or MOSFET available for working with LTspice."
What is your definition of high frequency? For some people, it is 1MHz, for others it might be 10GHz.
To make it a bit easier for you, the following few suggestions have manufacturer-supplied SPICE models: BF998 (N-ch DG MOS) BFR92AW (NPN BJT)
BFT92W (PNP BJT)
Your best bets for SPICE models for RF transistors are the NXP or Infineon websites.?Also, try the group's Files section. I suspect from your question, you haven't actually looked very hard yet.
Regards, Tony
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
Shikha wrote:
"Can any one suggest me high frequency BJT Transistor or MOSFET available for working with LTspice."
What is your definition of high frequency? For some people, it is 1MHz, for others it might be 10GHz.
To make it a bit easier for you, the following few suggestions have manufacturer-supplied SPICE models: BF998 (N-ch DG MOS) BFR92AW (NPN BJT)
BFT92W (PNP BJT)
Your best bets for SPICE models for RF transistors are the NXP or Infineon websites.?Also, try the group's Files section. I suspect from your question, you haven't actually looked very hard yet.
Regards, Tony
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Hassan wrote:
? ?"I have found either the .lib file or the symbol !!!?"
That is good.
The first thing to understand is that they are almost completely independent of one another.? A symbol is just an icon, nothing more.? LTspice has some of the symbols already.? In the Select Component (F2) menu, choose the [Misc] area, then you can find DIAC, SCR, and TRIAC symbols.
If you found .lib files, then you found their SPICE models.
Now all you need to do is: (A) include the .lib file in your simulation, and (B) associate the symbol with the model inside the library file.
To include the .lib file, first put the .lib file in the same folder with your schematic that uses it.? Then add this as a SPICE Directive on your schematic:
? ?.lib filename.lib
To associate the symbol with the model:
Right-click on the symbol body and make sure Prefix is set to X.
Open the .lib file in a text editor (such as Wordpad) to see what's inside it.? There should be a subcircuit definition for the part you want to use.? Scroll down until you find it.? It might look something like this:
? ?.SUBCKT 2N6071B MT2 G MT1
Now you know the actual name of the model: 2N6071B.? And you know the order of the pins: MT2, G, MT1.? There could be several .SUBCKTs in the same file, each for a different part.? Find the one you want.
Go back to your schematic.? Edit the name next to the symbol, and change it from "TRIAC" (or "SCR" or "DIAC"), to the name of the subcircuit you want to use ("2N6071B" in this case).
The tricky part is to make sure the order of pins is correct.
For a Triac, LTspice assumes the order of pins is MT2, G, MT1.? If the order differs from that, then you should edit the .lib file and change the pins in the above .SUBCKT line to make them in that order.? This may take a little effort to understand what the pins are, when they don't have those specific names.
Regards, Andy
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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
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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
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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
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
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
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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
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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.
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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)
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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!
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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!
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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
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Re: Sub circuit heat dissipation not showing
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. ?
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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
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Re: Sub circuit heat dissipation not showing
Hi .. No one has a reply to my question? Thanks Brad
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Tony Casey