| Electronics > Beginners |
| TL431 linear power supply |
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| not1xor1:
--- Quote from: imo on December 25, 2018, 09:39:31 am ---With a 6.3mA current source and 2n2 ser 100ohm comp. 3V/5A 25V/5A --- End quote --- I confirm the circuit works as showed in your screenshot. Il looks like the problems arises from the placement of the AC source that yields awful results when placed like I did. I've to check more carefully the subject to understand what is wrong. Thanks P.S. since I suspected something is wrong in your measurement method I made a quick transient test, switching between 5mA and 1A on 25V output and the output goes awry... huge oscillations... see below |
| iMo:
Measurement method?? - That is the question! :) I took the LT/ADI method - see the link above. You previously did with a simple AC sweep. Your oscillation - are you using zero ESR output capacitors? Below with "real capacitors", no oscillation, a small ringing w/ 160mVpp amplitude.. |
| not1xor1:
--- Quote from: imo on December 27, 2018, 02:25:04 pm ---Measurement method?? - That is the question! :) I took the LT/ADI method - see the link above. You previously did with a simple AC sweep. Your oscillation - are you using zero ESR output capacitors? Below with "real capacitors", no oscillation, a small ringing w/ 160mVpp amplitude.. --- End quote --- That is a different method but should yield similar results. I used models of real capacitors too... I also tried to add a resistor of 0.5 ohm in series to each capacitor with no result. BTW this is LTspice XVII x64 Jun 15 2018 running in linux. I tried both alternate and normal solver, 4 threads and single thread. No matter what I try I always get oscillations. Might that depend on the TL431 model I'm using here ...? :-// in the comment I read: --- Quote ---** Released by: Analog eLab Design Center, Texas Instruments Inc. * Part: TL431 * Date: 12/14/2009 * Model Type: Transient and AC * Simulator: PSPICE * Simulator Version: 16.0.0.p001 * Datasheet: SLVS543J - AUGUST 2004 - REVISED DECEMBER 2005 --- End quote --- |
| iMo:
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 :" |
| xavier60:
--- Quote from: not1xor1 on December 27, 2018, 08:14:20 am --- P.S. since I suspected something is wrong in your measurement method I made a quick transient test, switching between 5mA and 1A on 25V output and the output goes awry... huge oscillations... see below --- End quote --- I think that C1 and R17 should be made larger, I'd start with 1uF and 1K |
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