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UCC27201A: Boot strap capacitor

na na78
Guru 16770 points
Part Number: UCC27201A

Hi

The recommended value of bootstrap capacitor is between 0.022uF and 0.1uF.

If this bootstrap capacitor selection is not right, could it be possible to lead to violate the absolute maximum rating of VHB-VHS < 20V?

And it leads to device damage, possibly?

BestRegards

  • 0
    TI__Expert 3355 points
    Hi Na Na,
    Thanks for the question. I'm an applications engineer in the high power drivers team.

    The bootstrap capacitor is usually sized based on the capacitance of your switching device. Cgate is calculated using the gate charge and switching voltage level (Cgate = q/V). We typically recommend Cboot > 10*Cgate to ensure HB-HS voltage does not drop below the HB-HS UVLO threshold.

    If your bootstrap capacitor is too small, the HB-HS potential might drop below the UVLO threshold (6.7V) and turn off the high side. Too high of a value for Cboot will lead to longer start-up times as it will take more time to charge Cboot at start up.

    Both scenarios do not cause you to violate the VHB-VHS<20V abs. max rating, so the device should not be damaged due to Cboot sizing.

    I hope this helps you with your question. Could you please press the green button if it did?

    Otherwise, feel free to keep asking more questions.

    Best Regards,
    John