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Zener based negative turn off for bootstrap half bridge

Lucas Schulte9
Expert 6955 points
Other Parts Discussed in Thread: UCC27282, UCC27712

I'm looking to see if this approach of achieving negative voltage for turnoff would work for both channels of a bootstrapped half bridge driver. Ideally the solution stems from only one voltage supply but I'm open to suggestions. The other zener based negative turnoff approach won't work for me due to the duty cycle limitation, 

Respectfully,

Lucas Schulte

  • 0
    TI__Genius 13445 points

    Hello Lucas,

    Thanks for reaching out.

    Can you please clarify which bridge you intend to use for this application?

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    TI__Expert 6955 points

    Mamadoou,

    I was looking at something like the UCC27282. I wanted to keep the question generalized since boot strapped half bridge drivers tend to be of the same basic architecture. That way if this zener based negative turn off approach is confirmed to work, then it most likely would  work for other similar half bridge drivers as well. 

    Respectfully,

    Lucas

  • 0 in reply to Lucas Schulte9
    TI__Genius 13445 points

    Lucas,

    A single supply configuration using a zener diode and capacitor in parallel should work with the UCC27712 specifically assuming you do not have not long duty cycle operations (which from the fact that you're using bootstrap circuit seems OK). The is possible because of the wide VDD range on the UCC27712 to accommodate the bipolar gate drive. 

    On the other hand, depending on the power transistors, the UCC27282 may not work given the supply range (VDD and HB_HS) to maintain the negative voltage generated and the positive gate voltage. 

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    TI__Expert 6955 points

    Mamadou,

    This particular zener based approach will not work for as there is a duty cycle limit as stated in my original post.  My question is only concerning the  zener based solution as in my original post. 

    So would that particular zener based solution work for a half bridge driver (including but not limited to the UCC2782)? 

    Respectfully,

    Lucas

  • 0 in reply to Lucas Schulte9
    TI__Genius 13445 points

    Hello Lucas,

    Thanks for your feedback, sorry I missed the last part of your question.

    I do not recommend the zener based solution with the non-isolated bridge drivers because of the integrated boot diode connecting VDD to HB_HS (for some drivers like UCC27282) and the HS pins of the bridge ICs which are not suited for bipolar gate drive topologies.

    Regards,

    -Mamadou