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UCC27201: external bootstrap diode

HS FAE Germany
Mastermind 32240 points
Part Number: UCC27201

Hello,
customer wants to drive high gate charge mosfets (approx. >150nC) with switching freq. of 70KHz. Can he drive it with UCC27201 or does he need an external diode to improve drive capability.

Regards, Holger

  • 0
    TI__Mastermind 23155 points

    Hello Holger,

    Thank you for supporting the UCC27201. There are a couple of considerations for driving high charge MOSFETs regarding the boot diode.

    I would 1st confirm the average boot diode current required for driving the high side MOSFET. I will assume there is a single 150nC MOSFET, the current required will be the gate charge x fsw or 150nC x 70kHz = 10.5mA. This is well below the internal boot diode average current capability of 100mA.

    I would confirm the boot capacitance required: A simple target is allowing 1V drop for charging the MOSFETs Qg, Cboot = Qg/delta HB or 150nC/1V or 150nF. We recommend oversizing the boot cap for tolerance due to temp and voltage, so a 220nF to 330nF capacitor will be adequate.

    It looks like this application will be OK with the driver internal boot diode.

    Regards,

  • 0 in reply to Richard Herring
    TI__Mastermind 32240 points

    Hello Richard,

    thanks for explanation.

    Customer worried about the peak currents and the peak current capabilities of the bootstrap diode.

    Regards, Holger