TL431LI: Abnormal output voltage

Nam, Dino

Part Number: TL431LI

Dear team,

At below schematic, The output voltage of TL431LI is about 4.5V. I expected output voltage is 2.495V. but I don't understand the result.

Please review below schematic and let me know your opinion

Thank you.

over 3 years ago

0 Ben C over 3 years ago

TI__Mastermind 40675 points

Hi,

What is your expected IKA current going into the TL431LI? I don't think you have enough current going into the TL431LI. You might want to resize the resistor ratio of R7 and R13.

Ben

0 Nam, Dino over 3 years ago in reply to Ben C

TI__Expert 6285 points

Hello Ben,

Thank you for your comment.

I already tested with resizing the resister. R13 1M==> 10Kohm, R7 100K==> 1K but i got same result.

Do you mean resizing ratio of R7 and R13 is like R13 500K/R7 100K? Is it right?

Is there another point cause abnormal output? please let me know your opinion.

Thank you.

0 Ben C over 3 years ago in reply to Nam, Dino

TI__Mastermind 40675 points

Hi,

What if you short R18? Does your circuit work?

Ben

0 Nam, Dino over 3 years ago in reply to Ben C

TI__Expert 6285 points

Hello Ben,

I am sorry to bother you.

We found cause(layout issue) and solved problem.

Thank you for your strong support.

0 Ben C over 3 years ago in reply to Nam, Dino

TI__Mastermind 40675 points

Glad to be of help Dino!

Ben

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TL431LI: Abnormal output voltage