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UCC27201A: The selection of half bridge driver

Eric QI
Intellectual 620 points
Part Number: UCC27201A
Other Parts Discussed in Thread: UCC27201, LM5164

Hi,

1、According to the designed MOSFET,how to choose a  half bridge driver.

My biggest puzzle is how to calculate the required maximum current Ipk of the driver.

2、Suppose that I use a DC-DC for the half bridge driver.

Now I know the Ipk of the driver, how to calculate the power of DC-DC.

Thanks.

  • 0
    TI__Mastermind 21675 points

    Hello Eric,

    Thank you for the interest in TI half bridge drivers. Regarding the target gate driver current capability, the gate drive current and the total MOSFET gate charge, which can be viewed as an effective driver load capacitance, will determine the gate to source voltage rise and fall times. The gate drive strength with given MOSFETs will determine the switching times of the power MOSFETs.

    With a UCC27201 gate driver featuring 3A gate drive current you can estimate Vgs rise and fall times as below.

    If you have a MOSFET that is 60nC this is usually specified at 10V Vgs which results in 6nF effective capacitance.

    Using the typical equation I=C dV/dt solving for dt results in dt=CdV/I. For 6nF and 3A drive current dt=6nF x 10V/3A = 20ns.

    The ability of the driver to slew the MOSFET Vgs is the best way to estimate the driver current needs.

    Confirm if this addresses your questions, or you can post additional questions on this thread.

    Regards,

  • 0 in reply to Richard Herring
    Intellectual 620 points

    Thanks,Richard

    The next puzzle is that,if i want to use DC/DC switching regulators.

    How to calculate the power required by the power supply for the driver(UCC27201).

    Is it appropriate to use lm5164,for converter 48VDC to 12VDC?

    The maximum rated 1A output current of LM5164,is it enough to supply the UCC27201.

    Regards，

    Eric

  • 0 in reply to Eric QI
    TI__Genius 13650 points

    Hi Eric,

    Thank you for reaching out to E2E. Given it is Friday afternoon our expert will be out for the weekend.

    Please allow sometime for our expert to get back to you early next week.

    Best regards,

    Andy Robles

  • 0 in reply to Eric QI
    TI__Mastermind 21675 points

    Hello Eric,

    The average current required for driving the MOSFETs is primarily determined by the total MOSFET Qg and switching frequency. There is some additional quiescent current, or operating current of the driver but it will only be a few milliamps.

    The average current required to drive the MOSFETs is determined by: Iavg=Qg x fsw, where Qg is the total gate charge of the MOSFETs on both the LO and HO driver outputs and fsw is the switching frequency.

    The LM5164 is a 1A rated switching regulator so that is more than adequate to provide the gate driver bias.

    Regards,