Electronics > Beginners
TL431 linear power supply
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Kleinstein:
A larger value for R17 is likely a good idea. About half the values of R8 (feedback from the input) could be a good start.
1 µF for C1 would be really slow and only a start. The shown 2.2 nF seem to be in a reasonable range, when looking at simulations from IMO.

One should also keep in mind that the loop gain would change with the feedback divider.
not1xor1:

--- Quote from: imo on December 27, 2018, 08:39:54 pm ---Here is the latest LTspiceXVII, and with the latest Bordodynov library (LTspiceXVII_2018Dec21.zip).
Below the TL431s offerings..
PS: tried with several TL431 models and got similar results as above..

And the library is here, for the latest download go to "Additional links :"

--- End quote ---

OK, but what really matters is to know which kind of TL431 library you got.
The one I'm using clearly states: Model Type: Transient and AC.
The one you're using might be a coarser model... might it not?  :wtf:

(OK... I'm downloading the huge zip and will check that myself later  :D )
iMo:
Here with the 2n2 (C4 in my simulation) and R4 from 100-16k.
For 25V/5A pulses and 3V/5A pulses.

For 3V the R4s>=1k in order the simulation works "reasonably fast" (PS:With Behavioral model TL431A it simulates fine from 100ohm up).

With 25V the R4s>400ohm make more ringing.
iMo:

--- Quote from: not1xor1 on December 28, 2018, 10:05:21 am ---(OK... I'm downloading the huge zip and will check that myself later  :D )

--- End quote ---
A good move  :-+

Be careful with the installation of the Library.

You have to replace the 2 folders (examples, lib) in:
C:\Users\..user..\Documents\LTspiceXVII\
PS: make backup of your own models/parts.

Do not touch folders in:
C:\Program Files\LTC\LTspiceXVII\

After the start LTspice will reindex the new Library.
not1xor1:

--- Quote from: imo on December 28, 2018, 10:40:34 am ---
--- Quote from: not1xor1 on December 28, 2018, 10:05:21 am ---(OK... I'm downloading the huge zip and will check that myself later  :D )

--- End quote ---
A good move  :-+

Be careful with the installation of the Library.

You have to replace the 2 folders (examples, lib) in:
C:\Users\..user..\Documents\LTspiceXVII\
PS: make backup of your own models/parts.

Do not touch folders in:
C:\Program Files\LTC\LTspiceXVII\

After the start LTspice will reindex the new Library.

--- End quote ---

I already did that in past, but I prefer to add just the models I need.
BTW I use my own paths and just add them to the search path in LTspice settings.

In any case I see that there are 4 different TL431 models which added to the one I've been using so far are 5.
No wonder the same circuit may produce so different results... ;D

I guess the only way to know which one works better is to build a few different real circuits and compare the results.
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