UCC28711: Flyback startup problem

IgorR

Part Number: UCC28711

Tool/software:

In my design after power up the Vdd voltage keeps fluctuating between 8.1V and 21V and MOSFET never starts switching. What could be causing this behavior and what is the best approach to fix this?

over 1 year ago

0 Harish Ramakrishnan5 over 1 year ago

TI__Mastermind 24375 points

Hi IgorR

Thank you for reaching out.

The IC is most likely restarting because it has encountered a fault.

Please refer the following debug guides which might be helpful with the debug process.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/508706/trouble-shooting-startup-issues-with-ti-psr-flybacks-ucc28700-ucc28701-ucc28702-ucc28703-ucc28704-ucc28710-ucc28711-ucc28712-ucc28910-ucc28911-ucc28720-ucc28722-etc?tisearch=e2e-sitesearch&keymatch=UCC28712

https://www.ti.com/lit/an/sluaac5/sluaac5.pdf?ts=1725511561023&ref_url=https%253A%252F%252Fwww.google.com%252F#:~:text=The%20input%20bulk%20capacitor%20CIN,will%20cause%20a%20UVLO%20fault.

Regards,

Harish

0 IgorR over 1 year ago in reply to Harish Ramakrishnan5

Prodigy 85 points

Hi Harish,

I would like to share my schematic privately with you to speed up troubleshooting. We do have an NDA with TI.

0 Harish Ramakrishnan5 over 1 year ago in reply to IgorR

TI__Mastermind 24375 points

Hi IgorR,

Please send the schematics to harish.ramakrishnan@ti.com

Regards,

Harish

Power management

Power management forum

UCC28711: Flyback startup problem