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DRV8306: Fault Problem with DRV8306, CSD88584 Mosfet

ian lee
Prodigy 10 points
Part Number: DRV8306

Hi, experts.

I am encountering issues with the Motor Driver DRV8306 and Ti Mosfet CSD88584.

I chose this mosfet after observing it on TI's EVM Board, which utilized the DRV8306 and CSD88584 Mosfet.

My system comprises an ST microcontroller, a 3 Phase BLDC Motor (rated current 0.5A), DRV8306, and CSD88584 Mosfet.

For the past 1-2 months, everything has been fine. However, I recently identified some problems. When I power on (24V), the nFault LED, connected to check for errors, turns on every time. Even after resetting, it appears normal briefly but then returns to the nFault state.

Initially, I suspected the Gate Drive setting. I didn't connect a Gate resistor(Inrush current), and on Ti's EVM Board, there was no Gate resistor either. I read on the datasheet that a smart gate driver system doesn't require external components (diode, Gate resistor).

Concerning my IDRIVE setting, when I calculated Isource Qgd / tr -> 26nC / 24ns (External Mosfet CSD88584), it exceeded 1Amp. This seemed unreasonable, especially considering that I have observed rise times commonly ranging from 100ns to 300ns.

Secondly, the datasheet of the mosfet CSD88584 indicates a maximum switching frequency of 50kHz. Therefore, I set it to 50kHz. Is this inappropriate? If there are any errors in my calculations or settings, please advise.

I appreciate any guidance.

Regards.

IDRIVE Setting.(135mA/ 270mA Source / sink current setting)

  • 0
    TI__Mastermind 18840 points

    Hi Ian,

    Does the fault only appear when attempting to spin the motor or when the device is powered on and the motor is not commanded to spin? I suggest taking a look at our FAQ on debugging Hardware variant devices as it may better assist you in determining what is causing the fault: https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1160331/faq-debugging-faults-with-hardware-variant-devices.

    ian lee said:
    Concerning my IDRIVE setting, when I calculated Isource Qgd / tr -> 26nC / 24ns (External Mosfet CSD88584), it exceeded 1Amp. This seemed unreasonable, especially considering that I have observed rise times commonly ranging from 100ns to 300ns.

    Are you aiming for a 24ns rise time? Based on the IDrive setting you are using 100ns - 300ns of rise time is expected.

    ian lee said:
    Secondly, the datasheet of the mosfet CSD88584 indicates a maximum switching frequency of 50kHz. Therefore, I set it to 50kHz. Is this inappropriate? If there are any errors in my calculations or settings, please advise.

    We typically recommend using 20kHz, but if you prefer to use a higher switching frequency this is fine. Please do note that using higher switching frequencies will lead to higher switching losses.

    Regards,

    Joshua

  • 0 in reply to Joshua Horlander Cruz
    Prodigy 10 points

    Thanks for your answer. I'm going to try debugging with this list.