# TL431 Simulation help needed in LT Spice

#### mishra87

Joined Jan 17, 2016
851
Hi Guys,

I am trying to simulate the TL431 for for 4V output but i couldn't.
Can anyone help me out here ?

I do not find TL431 for LT Spice database so i use LT1009.
TL431 reference is at 2.5V and not i want to generate 4V output.

Could anyone guide me how to add TL431 in database and generate 4V at output ?

Thanks,

#### ericgibbs

Joined Jan 29, 2010
10,449
hi mishra,
Unzip and install this TL431.
E

Upgraded the zip to include the TL431.mod file

#### Attachments

• 1.3 KB Views: 5
• 1.1 KB Views: 8
Last edited:

#### Alec_t

Joined Sep 17, 2013
11,504
After unzipping the files, if you're running LTspiceXV11 under Win10 you can use Control Panel to add the paths to those files, or you can copy the sub file to your ...User/Documents/LTspiceXV11/lib/sub folder and the asy file to an appropriate ...User/Documents/LTspiceXV11/lib/sym/ sub-folder.

#### mishra87

Joined Jan 17, 2016
851
hi mishra,
Unzip and install this TL431.
E

Upgraded the zip to include the TL431.mod file
I installed TL431 file as per below >

.sym file in symbol folder and .lib file in lib folder but still see some error here !

#### ericgibbs

Joined Jan 29, 2010
10,449
hi m,
E

#### mishra87

Joined Jan 17, 2016
851
hi m,
E
Thank you so much !
It worked with these files. Now i got know exporting 3rd party model in LT Spice.

Is there there anyway to write a model for any components ?
Lets say i want to write a model for TL431, how to i write.

The 3 files are needed for simulation.
.Sym
.Lib
.Mod

I am highly interested to learn.

#### OBW0549

Joined Mar 2, 2015
3,503
I do not find TL431 for LT Spice database so i use LT1009.
Just for future reference, the LT1009 can NOT be used as a replacement for the TL431. The third terminal on an LT1009 isn't there to program the voltage as it is with the TL431; rather, it's a "trim" input that allows the LT1009's voltage to by adjusted by up to ±5% to correct for manufacturing tolerances or other tolerances in the application circuit.

Always read a part's data sheet before you attempt to use it. You'll save yourself a lot of trouble.

#### crutschow

Joined Mar 14, 2008
25,247
What's the purpose of V2 in your second circuit?

#### ericgibbs

Joined Jan 29, 2010
10,449
hi Carl,
That 2nd circuit is one I posted [post #2] together with the TL431 zip, so that the TS could do a quick test of the unzipped TL431 files, its not related to the TS circuit.
Eric

#### mishra87

Joined Jan 17, 2016
851
What's the purpose of V2 in your second circuit?
For me it is two series Li Ion battery !

#### ci139

Joined Jul 11, 2016
1,671
TL431 like thingy :
Code:
* Experimental Spice Model of
*$* last modified 2017.09.11 - 17:27 UTC+3h CE * x x 4 3 1 x x Shunting Voltage Regulator * * * * * * * FbAnCa* * * .SUBCKT AZ431 1 2 3 * - - - - - - R A C - - * ** Resistors ** R1 13 14 {jRo*25} R2 14 12 {jRo*24} R3 14 15 {jRo*24} R4 16 2 {jRo*3.4} R5 12 17 {jRo*2.7} R6 8 10 {jRo*11} R7 3 5 {jRo*1.8} R8 3 6 {jRo*1.8} R9 9 11 {jRo*.33} R10 11 2 {jRo*48} ** Capacitors ** C1 15 10 20p C2 3 4 20p ** Diodes ** D1 2 4 AZrppPd D2 2 3 AZrppPd ** Transistors ** ** PNP ** Q8 7 7 5 AZsdtmP {jSa*2} Q9 4 7 6 AZsdtmP {jSa*1} ** NPN * Q1 4 17 2 AZsdtmN {jSa*1} Q2 3 1 13 AZsdtmN {jSa*2} Q3 4 4 1 AZsdtmN {jSa*3} Q4 12 12 2 AZsdtmN {jSa*.9} Q5 15 12 16 AZsdtmN {jSa*7.2} Q6 10 15 2 AZsdtmN {jSa*1} Q7 7 13 8 AZsdtmN {jSa*1} Q10 3 4 9 AZsdtmN {jSa*2.5} Q11 3 11 2 AZsdtmN {jSa*50} ** Parameters ** .param jRo={4k/9} ** - .param jSa={(1/50)*(1k85/700)} ** Models ** ** 1N4148 ** .model AZrppPd D(Is=2.52n Rs=.568 + N=1.752 Cjo=4p M=.4 tt=20n + Iave=200m Vpk=75 mfg=OnSemi type=silicon) ** 2N2222 BF=200 ** .model AZsdtmN NPN(IS=1E-14 VAF=100 + BF=180 IKF=0.3 XTB=1.5 BR=3 + CJC=8E-12 CJE=25E-12 TR=100E-9 TF=400E-12 + ITF=1 VTF=2 XTF=3 RB=10 RC=.3 RE=.2 Vceo=30 + Icrating=800m mfg=Philips) ** 2N2907 BF=250 ** .model AZsdtmP PNP(IS=1E-14 VAF=120 + BF=180 IKF=0.3 XTB=1.5 BR=3 + CJC=8E-12 CJE=30E-12 TR=100E-9 TF=400E-12 + ITF=1 VTF=2 XTF=3 RB=10 RC=.3 RE=.2 Vceo=40 + Icrating=600m mfg=Philips) .ENDS AZ431 *$
+ there are more at
http://ltwiki.org/index.php?title=Components_Library_and_Circuits
+ one included in http://ltwiki.org/index.php?title=Simulating_the_MC34063_in_Inverter_Configuration_with_an_Accurate_TL431A_Model