LT1171 model: syncronization not working

#90047

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 0.3μs.?

> ...

>?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]

#90026

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]

#90025

Write a message...

BS250 & BS170 SIM

#90083

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

#90060

开云体育

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

?

With best wishes DESIGN IT IN! OOO – Own Opinions Only

J M Woodgate and Associates Rayleigh England

?

Sylvae in aeternum manent.

?

Show quoted text

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

#90022

Hi .. No one has a reply to my question? Thanks Brad

Need spice model for IR TX and RX

[email protected]

#90064

Hi Team,

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

Regards,

Dhanabal T

?????????

Re: Mechanical switch

#90020

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

#90018

Go to Text editor file?bounce.asc.

Replace?.lib ..\sym\Source\source.lib to?.lib source.lib

I am sorry.

Bordodynov.

?

Re: Mechanical switch

#90021

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@...>:

Show quoted text

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

#90019

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]

#90016

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

#90017

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

#90014

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.

?

Re: Thyristor library

#90011

开云体育

Hassan wrote:
"I am new here..."

In that case the suggestion in the welcome message to search the group's Files section will still be fresh in your mind. Had you done this you might have found this:

Additionally, LTspice already comes with SCR and TRIAC symbols in the "Misc" folder.

No need to search "all over the internet"!

Regards,
Tony

Re: Thyristor library

#90013

Hello Hassan.
The fastest way is to download a my folder from LTwiki.org
Go to  and

(A Large LTspice Folder from Bordodynov).
LTC&#92;LTspiceIV&#92;lib&#92;sym&#92;EXTRA&#92;ST&#92;SCR&#92;
LTC&#92;LTspiceIV&#92;lib&#92;sym&#92;EXTRA&#92;ST&#92;TRIAC&#92;
LTC&#92;LTspiceIV&#92;lib&#92;sym&#92;EXTRA&#92;TECCOR&#92;SCR&#92;
LTC&#92;LTspiceIV&#92;lib&#92;sym&#92;EXTRA&#92;TECCOR&#92;TRIAC&#92;

Bordodynov.

03.08.2016, 10:17, "someone00044@... [LTspice]" <ltspice@...>:

Show quoted text

Hello together,
I am new here and I've searched all over the internet to get the full library of a Thyristor but I couldnt :( I have found either the .lib file or the symbol !!! could anybody kindly upload the full library so that we can use it directly. Please feel free to share your experience :)) thanks in advance!
Hassan

Re: Mechanical switch

#90012

Hi.
See file bounce.zip in TEMP folder.

Bordodynov.

03.08.2016, 09:44, "Vlad imbvlad@... [LTspice]" <ltspice@...>:

Show quoted text

There is a spark gap model in the group's files, maybe it can be combined with the bounce relay?

Vlad
______________________
ltspicegoodies.ltwiki.org -- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Mechanical switch

#90008

There is a spark gap model in the group's files, maybe it can be combined with the bounce relay?

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Current Dependent Voltage Source

#90009

> What if I want to input a table of data I measured from a unit?? I have multiple input/output pairs that I want to use.? How would I do this?

Then you don't need a current/voltage dependent current/voltage source, just a behavioural source or a VCVS/CCVS. For behavioural sources, the syntax is:

table( f(x), time0, value0, time1, value1, ...)? ; f(x) = any time-dependent (or not) quantity

and for CCVSs/VCVSs:

table( time0, value0, time1, value1, ...)? ; the input is implicitly used.

These are assuming you need an input that needs to be passed (transformed) through the table. Otherwise, if all you need is to generate data based on a table, a simpe current/voltage PWL="file" source will do.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Thyristor library

[email protected]

#90010

Hello together,
I am new here and I've searched all over the internet to get the full library of a Thyristor but I couldnt :( I have found either the .lib file or the symbol !!! could anybody kindly upload the full library so that we can use it directly. Please feel free to share your experience :)) thanks in advance!
Hassan