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Original question:

DRV8350: Burned chip and VGLS failed

DRV8350: Current capacity that can be supplied by VGLS

Daisuke Higa
Genius 4335 points
Part Number: DRV8350

Tool/software:

Hi support team all.

About the current capacity that VGLS can supply

The data sheet for VGLS states that it can supply 25mA of current.

This 25mA is only when supplying to the outside, right?

It is used internally to drive the low-side gate, but I understand that it can output several hundred mA.

It says that VGLS supplies current to the low-side gate drive circuit, but when driving three low-side MOSFETs simultaneously, if IDRIVE is set to its maximum value, it needs to be capable of outputting a maximum current of about 3A. Can I assume that this can be output from VGLS?

Best regards,

Higa

  • +1
    TI__Mastermind 26566 points

    Hi Higa-san,

    The 25mA of current capability for VGLS is the average current capability of VGLS. When turning on the low side MOSFETs using the max IDRIVE, this current is only applied for a short duration until the Qg of the MOSFET has been supplied to turn it on. The capacitor on VGLS can supply this peak current for the short period of turning on a FET. Thus the average current is much lower. IVGLS = number of low side FETs switching * PWM switching frequency *MOSFET Qg. Note: MOSFET Qg would be the total effective MOSFET Qg, which would be twice the MOSFET Qg in the case of parallel FETs. Additional average current needs to be considered such as an external Rgs resistance on the low side. 

    Regards,

    Anthony Lodi

  • 0 in reply to Anthony Lodi
    Genius 4335 points

    Hi Lodi-san

    Thank you for your prompt reply.

    I understood well.

    BR

    Higa

  • 0 in reply to Daisuke Higa
    TI__Mastermind 26566 points

    Great to hear!

    Regards,

    Anthony Lodi