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DRV8343-Q1: Independent MOSFET drive mode in BLDC application, can it protect MOSFET in shoot-through of bridge?

Jass Jin
Intellectual 2465 points
Part Number: DRV8343-Q1
Other Parts Discussed in Thread: DRV8329-Q1, DRV8305-Q1, DRV8334

Hi expert,

My customer need dead-time to be less than 500ns. In the defaulst 6 PWM mode, the minimum dead-time is 500ns.

So we change to independent MOSFET mode. In this mode, 8343 don't care about the dead-time of input PWM wave.

If MCU send the wrong PWM, the MOSFET in half-bridge may shoot-through, can 8343 protect these two mosfet in this case?

The Qg of MOSFET is 49nC(0-15V), the rdson is 1.7mohm. The part number is ZMSA016N04HNC.

Thanks!

  • 0
    TI__Genius 14795 points

    Hi Jass,

    What variant of DRV8343-Q1 is the customer using? SPI or Hardware?

    As far as I know, automatic dead time insertion is the preventative measure the driver has in order to avoid shoot through, using independent mode essentially disables this preventative measure.

    Regards,

    Yara

  • 0 in reply to Yara Al Shami
    TI__Intellectual 2465 points

    They are using SPI version. The minimum dead time is too large, we need 100-250ns deat-time now, wo we use independent mode.

  • 0 in reply to Jass Jin
    TI__Genius 14795 points

    Hi Jass,

    I'll really have to check with my team on this, as far as I know dead time insertion is the only preventive measure for shoot through so if you are using a mode that has it disabled you will have not protection against shoot through if the MCU sends incorrection PWM signals

    Regards,

    Yara

  • 0 in reply to Yara Al Shami
    TI__Intellectual 2465 points

    Our OCP glitch is 4.75us and the SOP of MOS is 10us, can I consider 8343's OCP can protect MOSFET?

  • 0 in reply to Jass Jin
    TI__Genius 14795 points

    Hi Jass,

    I can not advise you to rely on OCP to protect the MOSFET in the instance of shoot through caused MCU failure in independent mode if the datasheet doesn't explicitly say as such. Datasheet explains there is no dead time inserted in independent mode and this is really for the purpose of driving solenoids where both high and low side need to be one. 

    Have you considered any of the following devices instead that have lower dead time? DRV8305-Q1, DRV8334, or DRV8329-Q1?

    Regards,

    Yara