Hello, I am confused regarding a component TL431 pin out.
In LTSPICE model:
reference is 1
anode is 2
cathode is 3
but in the data shhet is another pin order .
So i need to connect the layout as shown below?
correct?
Thanks.

https://www.digikey.co.il/en/produc...a5ByHx1IY32w-dzUZpsNsdvorpbvwoQkWDQmkLronS02C

 

The pin numbers in a schematic do not have anything to do with the pin numbers on a specific package (i.e. footprint.) A device often has multiple package options with different pin numbers. There is usually just one schematic symbol for the device. In my CAD software, I implemented a map that relates the schematic pin names (they are not even numbers, they are text) to package pin numbers.

 

Hello, So my layout is correct? regarding cathode anode ref for positive output?
Thanks.

 

Hi yef
This is my TL431 file for comparison.
E

*****************************************************************************
* TL431 MACROMODEL ***************3-26-92************************************
* REV N/A ****************************************************************DBB
*****************************************************************************
* REFERENCE
* | ANODE
* | | CATHODE
* | | |
*.SUBCKT TL431 1 2 3
* Reverse symbol
* Anode Cathode Ref adjusted to LTSPICE symbol
.SUBCKT TL431 2 3 1
V1 6 7 DC 1.4V
I1 2 4 1E-3
R1 1 2 1.2E6
R2 4 2 RMOD 2.495E3
R3 5 7 .2
D1 3 6 DMOD1
D2 2 3 DMOD1
D3 2 7 DMOD2
E1 5 2 POLY(2) (4,2) (1,2) 0 710 -710
.MODEL RMOD RES (TC1=1.4E-5 TC2=-1E-6)
.MODEL DMOD1 D (RS=.3)
.MODEL DMOD2 D (RS=1E-6)
.ENDS

 

Hello, Its the same thing, So did i connect the chip correcly ?
So i wont have a surprise when I'll get the PCB.

* REFERENCE
* | ANODE
* | | CATHODE
* | | |
*.SUBCKT TL431 1 2 3

 

I picked the wrong chip
I need TL431, now the correction is ok?
Thanks.

 

Hi yef,
The numbers are for model nodes, not IC Body pins.
Re look at this correction.
E
*.SUBCKT TL431 1 2 3
* Reverse symbol
* Anode Cathode Ref adjusted to LTSPICE symbol
.SUBCKT TL431 2 3 1

 

You are using the incorrect device, TL431 vs TL432 and mixing up different packages.

 

Hello , Yes but 1 is refrence 2 is anode and 3 is cathode still.
so this is my orientions.

 

 

but in the data shhet is another pin order .
So i need to connect the layout as shown below?

Yes.
To reiterate, the Spice model shows a node number, not a pin number.
It is normally unrelated to the actual package pin number, since that can vary between different packages.

 

When designing the TL431 footprint for the PCB, ignore the spice model.
Use the schematic and pin orientation shown on the datasheet for the physical package you will use.

 

Hello, I also have a negative reference structure shown below in net Vg1.

https://www.digikey.co.il/en/produc...o4QQIpFJLJWAnuLm-aL7Aw8PpXpvRACakcRoBGyQY0sJw

 

Hello, I also have a negative reference structure shown below in net Vg1.

https://www.digikey.co.il/en/produc...o4QQIpFJLJWAnuLm-aL7Aw8PpXpvRACakcRoBGyQY0sJw

View attachment 337090View attachment 337089View attachment 337088View attachment 337087

If you don't have EE symbols to draw the circuit then you can refer to the symbols in my Blog.

Blog entries by ScottWang

 

I also have a negative reference structure shown below in net Vg1.

With load2 = 40kΩ and load2 = 1kΩ in your schematic, the regulated voltage (Vg1) is -2.57V, which is an odd value.
Is that the voltage you want?

 

Yes , It is.
Thank you very much.