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UCC289x Active Clamp controller

Hong14351
Prodigy 190 points
Other Parts Discussed in Thread: UCC2897A, UCC28084

I intend to use active clamp controller UCC289x for a stepup converter application. Input voltage 6V, input current <=20A, output voltage 24V nominal. I have a bias supply on board which provide 13.5V house keeping power for the UCC289x controller chip. My question is, is it practical to use P-mosfet as clamping switch? I am wondering the input voltage is only 6V, the aux drive output could go as low as GND, barely enough to drive the P-mosfet. N-mosfet will work for this application, but the more complicated driving circuit will likely take away the cost benefit, compare to a UCC2808x based push-pull topology circuit.

Compare to a push-pull converter for this step-up application, will active clamp forward topology provide much efficiency benefits?

Thank you. David

 

  

 

  • 0
    TI__Guru 73325 points

    The drive voltage on AUX pin to P-mosfet gate and source is not related to the input voltage. Instead, it is related to the VDD which is 13.5V from your house keeping power. The AUX-pin is not directly connected to the P-mosfet. The datasheet shows typical connections.

  • 0 in reply to Hong Huang
    Prodigy 190 points

    Hello Hong, Thank you for the reply.

    Do you have any comment regarding the advantage/disadvantage of the active clamp forward topology (UCC2897A) compare to push-pull topology (UCC28084) for this DC/DC step up application? (Max 6V/20A input, to 24V nominal output)

    Thank you. David