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DRV8353R: Low side gate driver of DRV8353 keeps breaking

Alexander Gomez
Prodigy 130 points
Part Number: DRV8353R

We have broken at least 6 low side gate drives on DRV8353R ICs with software, even with no motor connected. We noticed that the high side is provided with Zener clamp diode protection, but not the low side.

Do we need to implement a separate, external Zener diode clamp on the low side, which is the only side that keeps breaking, or is there a different solution that has been implemented before? Has anyone seen this particular problem with this particular chip?

  • 0
    TI__Mastermind 18450 points

    Hi Alexander,

    Thank you for your post!

    The purpose of the Zener diode on the gate to source of the high side MOSFET is a safety feature to prevent an overvoltage event on the gate of the high side MOSFET in the case of an accidental short of the high side source to ground. Since the high side MOSFET gate voltage is being supplied from the charge pump (which is about 10-12V higher than VM), if the source of the high side MOSFET is shorted to ground during operation, then it is very likely to exceed the Vgs ratings of the high side MOSFET. That is why our device integrates a Zener diode on the high side VGS to limit the Vgs voltage if an accidental high side source short to ground event occurs. The low side MOSFET would not have this problem since it is not driven by the charge pump, so there is no need to use a Zener diode on the low side gate of the device.

     

    I have a few questions for you:

    1. Does the driver throw a fault after the driver gets damaged? If so, what fault are you reading in the Fault Status 1 or VGS Status 2 registers?
    2. What MOSFETs are you using?
    3. What is your Idrive settings?
    4. Is it happening on the same phase? Or different phases?
    5. Can you provide a waveform showing the low side gate to source signals?

    It is possible that parasitic voltage spiking on the board could be causing some of the device's absolute maximum ratings to be exceeded. Sometimes parasitic voltage spiking can occur on the source and/or gate of the MOSFET/s due to trace inductance, too high Idrive, and/or other factors. Reducing the Idrive could be a potential solution to the issue. 

    Regards,

     

    Anthony

  • 0 in reply to Anthony Lodi
    Prodigy 130 points

    Hi Anthony,

    Thanks for the quick reply. Here are answers to the questions:

    1. We're using this part: DRV8353RHRGZT   - It's all hardware configured - there are no status registers we can read.
    2. MOSFET - IAUS300N08S5N012

    3. Idrive is pulled high by 18kohm which is equal to a 700mA gate drive current. 

    4. Different phases

    5. Working on obtaining waveform.

    Does 700 mA seem high for Idrive and could that induce parasitic voltage spikes? The original intent was to have two MOSFETs in parallel per phase, but that was not needed.

    Thanks,

    Alex

  • 0 in reply to Alexander Gomez
    TI__Mastermind 18450 points

    Hi Alex,

    Thank you for the additional information!

     Based on the MOSFETs you are using it seems that 700mA is going to be too high for Idrive and will likely result in parasitic voltage spikes. From what I can tell from the datasheet the MOSFETs have a Qgd of about 40nC, so with an Idrive of 700mA that would be about 40nC/700mA = 57ns rise time which is quite fast for most systems to handle. The gate to source waveforms will give a better indication if it is too high of an Idrive. I would recommend starting with the 150mA/300mA Idrive setting (Idrive pulled low with 75kohm tied to AGND), and then if it seems like your system can handle that Idrive well (without parasitic spiking on the gates), you could try to increase the Idrive and continue to monitor the gate voltage to make sure that there is no undesired parasitic ringing.

    Regards,

    Anthony