UCC28950: Phase Shifted Full Bridge DC-DC converter output protection question

Buddika Sumanasena

Part Number: UCC28950

Hi All,

This question is about an output protection circuit – I suppose – used in a phase shifted full bridge DC-DC converter reference design using the UCC28950 controller.

I have attached an image of the circuit section. It is enclosed by the red rectangle in the image. This block of components seems to be some over voltage protection mechanism. Please correct me if I am wrong here. Does anyone know how exactly this works and how should I go about selecting components for this. If you can refer me to an application note or even a book that describes this it would be great.

This is the Ti reference design I took this from http://www.ti.com/lit/ug/tidu248/tidu248.pdf.The circuit part is in page 63.

Best regards

Buddika

over 8 years ago

0 Brian Johnson96 over 8 years ago

TI__Expert 3200 points

Hi Buddika,

The circuits you have highlighted in your red box are implementing a RCD clamp circuit. We recommended this network, reference the "UCC28950 600W Phase Shifted Full Bridge Design Review/Application Report" found at www.ti.com/.../slua560c.pdf

I do not have a step by step procedure for a UCC28950 RCD clamp circuit design. I suggest you look at the document "Snubber Circuits: Theory, Design and Application" at www.ti.com/.../slup100.pdf for designing the RCD voltage snubber in clamp mode.

Power management

Power management forum

UCC28950: Phase Shifted Full Bridge DC-DC converter output protection question