• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 64 subscribers
  • Views 66 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC28750: DC-DC converter

Yann Querec
Prodigy 10 points
Part Number: UCC28750

Tool/software:

Hello,

I am trying to make 24V to 5V converter with the UCC287506DBVR. You can see the converter on the schematic below.

When I power it up I don't have any oscillation on the DRV pin while I should have 100kHz PWM signal.

I measured 24V on VDD, 0V on CS, 5V on FB, 2.5V on FLT and 0V on DRV.

Do you have any idea why the DRV pin is always 0V ?

Best regards

Yann

  • 0
    TI__Guru 50090 points

    HI Yann,

    You might be damaging the device. While 24V does not violate the absolute maximum voltage rating of the VDD pin, without resistance between the 24V rail and the VDD pin, there is nothing limiting the current in the 12V clamp for the gate drive. 

    Actually adding a resistor and then using the aux winding to create an 18-20V VDD rail would help improve efficiency a bit.