UCC28250: how to determine ramp resistance and capacitance in ucc28250

gu chenjie

Part Number: UCC28250

I have a 300v to 48v push-pull dc-dc using UCC28250. because the input voltage already higher 75V, Can you let me know how to determine ramp resistance and capacitance? and how to select premary-side ovp resistance?

over 8 years ago

0 Peter Meaney over 8 years ago

TI__Mastermind 31580 points

Hi

I have asked one of our engineers to reply to your post. You should see a reply soon.

Regards

Peter

0 Brian Johnson96 over 8 years ago in reply to Peter Meaney

TI__Expert 3200 points

Hi Gu,

In the UCC28250 datasheet, there is design help on setting the Ramp and OVP component choices. RAMP starts on page 17 and OVP starts on page 24. The application section starting on page 31 also has some examples. You can see there are several design inputs needed from you in order to calculate the final component values. There is also an Excel design tool at: www.ti.com/.../toolssoftware that may help you in your design as well.

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UCC28250: how to determine ramp resistance and capacitance in ucc28250