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UCC21222: Overshoot between upper and lower bridge on UCC21222

Zoe Yang
Intellectual 2210 points
Part Number: UCC21222


My customer is evaluating on UCC21222. Overshoot will happen when output is open loaded and loaded. The deadtime is set up to 100ns from hardware and in software added 500ns as well. The switching frequency is 40kHz.in schematic R345 is NC and DT pin is connected to ground through resistor. Do you have any comments on whether this happened? 

 

  • 0
    TI__Genius 9556 points

    Hi Zoe,

    Thank you for providing these useful screenshots!

    Does the DT resistor also have a capacitor in parallel? This capacitor is there to help with noise immunity. For larger values of DT, it is recommended to place a ceramic capacitor in parallel with the deadtime resistor.

    This also might have been a case of dv/dt induced turn-on due to Miller current. To mitigate the risk of this occurring, it is recommended to have a pull-down resistor (typ. 5.1k-20k) placed as close to the gate as possible. 

    Hope this was helpful!

    Best regards,

    Hiroki