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DRV8300: when using DRV8300，high side MOS and Low side MOS be short at the same time

user6360875
Intellectual 280 points
Part Number: DRV8300

hi TI member

--when using DRV8300 in motor control , 

sometimes  we found the  high side MOS and low side MOS  turn short at the same time ,the bus line current may larger than  200Amps  （I guess）

power supply is a Lithium battery pack;

check as follows , Q5 and Q6  short --------- Drain 、source、Gate  are  all short  between each other;

--DRV8300 itself  has the dead time protection , so   in which condition ,  will cause the above case , i can't figure out it ,   

we didn't do any restrict  in our software ,pls get that

plz help 

Thanks~~~

plz

  • 0
    TI__Mastermind 23356 points

    Hello,

     I will consult with the team and aim to provide feedback before end of next week.

    Best Regards,

    Akshay

  • 0
    TI__Mastermind 23356 points

    Hello,

    Thank you for your patience.

    In order to better assist you, I would like to know which variant of drv8300 is being used?

    If you are experiencing a shoot-through condition with both high side and low side mosfet turning on then it is possible that the dead time chosen is not sufficient. On some variants of DRV8300 you can increase the deadtime using a resistor placed between DT pin and GND.

    The deadtime is a set time added to prevent both HS and LS from conducting at the same time.

    We can see both fets conducting at the same time if the rise/fall time is very fast.


    Trise/fall = Qgd/Isource/sink


    I looked up the Qgd of the fet (BSC070N10NS5) and saw the value of 6nC. So, with I drive at 750mA we get a rise time of 6nc/0.75A = 8ns. This is extremely fast and we typically recommend a rise/fall time of 200/100ns for a fast switch. The gate resistor should help with this but it might not be enough.

    Waveforms of Vdrain, SHx and GHx might be helpful in debugging this issue.

    Best Regards,
    Akshay

  • 0
    TI__Mastermind 18981 points

    Hello, 

    Closing thread for now due to inactivity - can you let us know if the problem has been resolved? 

    Please let us know if further support is needed on this question. Thanks 

    Best Regards, 
    Andrew