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DRV8300: Mosfet bridge hot even when no load

Dinh Le
Prodigy 50 points
Part Number: DRV8300

Hi

I'm design a BLDC driver with schematic as below.

I got an issue that all mosfet (P/N HYG015N10NS1TA) getting hot when no load, ~ >50oC. I try many difference gate resistor but it still hot.

My PWM frequency is 48kHz, if I decrease to 24kHz, the temperature also decrease a bit, to ~47 - 48oC,

I have large deadtime. So I think It not cause by shoot through current. I also measure output, Vgs voltage and all seem correct (no ringing, correct voltage).

I have try remove all subber RC (R131,C56, C151, R134....) but nothing change.

I have difference circuit with the same schematic but using other mosfet, part number (BSC030N10NS5SC), and it not get this issue.

please recommend me a solution.

By the way, if output of bridge is no overshoot, ringing, should I decrease gate resistor to very low value (ex 1ohm, 2ohm) to get sharp rise time, fall time of mosfet. I want to cut down power dissipation.

Thanks

  • 0
    TI__Genius 12231 points

    Hi Dinh Le, 

    Thank you for your question.

    Allow us to look over your schematic to determine a suitable recommendation for the HYG015N10NS1TA issue and power dissipation inquiry.

    Will aim to provide a follow-up by the end of the week.

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 50 points

    Thanks Joshua. Looking forward to hearing from you

  • 0 in reply to Dinh Le
    TI__Genius 12231 points

    Thank you for your patience, Dinh.

    After looking through your schematic and both MOSFET specifications, the problem might be that the HYG015N10NS1TA has a much longer switching time primarily due to its Qgd being nearly 4x larger than the BSC030N10NS5SC (50 nC vs 14 nC).

    This longer switching time coupled with the gate resistance of 47 ohm could be the cause of the overheating. 

    I recommend that you significantly decrease your gate resistance to <15 ohm if using the HYG015N10NS1TA, as you suggested, in order to increase your gate drive current so that Vds slews quicker. 

    It would be helpful if you could also provide scope measurements of the MOSFET switching to better determine if that is the cause.

    Best Regards,

    -Joshua

     

  • 0 in reply to Joshua Maize
    Prodigy 50 points

    Thank Joshua.

    I have tried decrease gate resistant to 12ohm, but it still hot. 

    I used value calculated from this tool https://www.ti.com/lit/zip/slvrbm5. But it still hot. 

    Could you please explain that why mosfet getting hot when no load? There are no load current, no shoot through current (because of large deadtime). so what make it hot?

  • 0 in reply to Dinh Le
    TI__Genius 12231 points

    Hi again Dinh, 

    Could you provide the other circuit schematic using the BSC030N10NS5SC that didn't heat up as well as the PCB layout for both MOSFETs if you have them available? It is very odd that one similar MOSFET is working so much better over the other, so it is possible it may be a layout-related issue as well. 

    We will continue looking into this heating issue and come up with a viable recommendation when possible.

    Thank You and Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 50 points

    Hi Joshua

    The schematic using the BSC030N10NS5SC exactly same to HYG015N10NS1TA.

    Here is layout of 2 PCBs.

    https://1drv.ms/f/s!Ao2WcIDxKUWtkuJ1oET9Xf0iP06w6w?e=4PLVbB

    (Because of policy of my company, I have deleted the unrelated section)

  • 0 in reply to Dinh Le
    TI__Genius 12231 points

    Hi DInh,

    Thank you and no worries, I understand. 

    With this added info my team and I will continue looking into the issue and aim to have an update for you as soon as we can.

    Best Regards,

    -Joshua