UCC256402 :UCC256402

Abdellah MORSLI

Prodigy 20 points

Part Number: UCC256402

Why i obtiend 0V on FB given that LL/SS pin gives me 5V

over 1 year ago

0 Jonathan Wong over 1 year ago

TI__Genius 10515 points

Hello Abdellah,

Can you please elaborate on your problem and give a schematic, waveform, etc.? As you can see by the internal block diagram, the voltage of FB will depend on how much current the FB pin can source and should not depend on the LL/SS pin voltage.

If you are seeing no voltage on the FB pin, it is likely because the optocoupler is open, which means your feedback loop is designed incorrectly.

Regards,

Jonathan Wong

0 Abdellah MORSLI over 1 year ago in reply to Jonathan Wong

Prodigy 20 points

Bonjour Jonathan,

je vous remercie pour votre réponse, vous trouverez ci dessus un tableau qui résume tous les composant utilisé dans le circuit.UCC25640x Design Calculator Rev5 (version 1).xlsx

0 Abdellah MORSLI over 1 year ago in reply to Abdellah MORSLI

Prodigy 20 points

Voici aussi les résultats obtenus sur l'oscilloscope pour VCC, RVCC dans IMG1 , et FB , LL/SS dans l'image 2

0 Jonathan Wong over 1 year ago in reply to Abdellah MORSLI

TI__Genius 10515 points

Hello Abdellah,

Placing English translation below for future reference and searchability:

"Thank you for your answer, you will find above a table that summarizes all the components used in the circuit. Here are also the results obtained on the oscilloscope for VCC, RVCC in IMG1, and FB, LL/SS in image 2"

To clarify the oscilloscope captures, is the following correct?

Image 1

Purple = VCC
Yellow = RVCC

Image 2

Purple = LL/SS
Yellow = FB

Please keep all E2E posts in English and not French. TI only offers E2E support in English and Chinese. We will provide an answer shortly.

Regards,

Jonathan Wong

0 Manikanta Pallantla over 1 year ago in reply to Jonathan Wong

TI__Genius 16155 points

Hi Abdellah,

Please ensure that the resonant tank meets the maximum gain requirement. The maximum gain obtained in your design does not meet the maximum gain criteria.

After you fix the tank parameters, please use the debugging guidelines given in the following app note for tuning components around the controller.

https://www.ti.com/lit/pdf/sluaaj7

Regards

Manikanta P

0 Abdellah MORSLI over 1 year ago in reply to Jonathan Wong

Prodigy 20 points

yes, it was like you mentioned

0 Manikanta Pallantla over 1 year ago in reply to Abdellah MORSLI

TI__Genius 16155 points

Hi Abdellah,

What do you mean by this?

Abdellah MORSLI said:
yes, it was like you mentioned

Regards

Manikanta P

Power management

Power management forum

UCC256402 :UCC256402