UCC28700-Q1: I used this chip for 12V to 20V flyback DCDC.

Mingkai Mu

Part Number: UCC28700-Q1

Hi,

I used this chip for 12V to 20V flyback. I am not sure if this chip is suitable for this application or not.

To run it, I used another boost converter to supply it VDD to 25V, because the turn on voltage is above 12V. When it starts, the controller generated three pulses and then stop. I think it entered fault mode.

I guess it may go to the line sensing error. I wanna ask if this is a correct way to use this chip, and how can I fit it into this application.

Thanks.

over 6 years ago

0 Emily Kong1 over 6 years ago

TI__Expert 3350 points

Hi Mingkai,

You are correct, the three pulses are an indication that a fault has been tripped. This is what is shutting down your controller. There are a few different conditions that can cause a fault mode; they can be found in section 7.3.2 (page 12) of the datasheet www.ti.com/.../ucc28700-q1.pdf. This is an additional application report that can help you identify problems in your design that may be causing this: www.ti.com/.../slua783.pdf

Best,
Emily

0 Mingkai Mu over 6 years ago in reply to Emily Kong1

Prodigy 50 points

Hi Emily,

The issue is solved. It goes to line sensing fault. After I reduced Rs1, the flyback started to work.

Thanks,

Mingkai

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UCC28700-Q1: I used this chip for 12V to 20V flyback DCDC.