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DRV8320: Condition of recovery from GDF

NY
Expert 3040 points
Part Number: DRV8320


The GDF fault release condition states that "the gate driver failure status has been resolved", 
but I think that the failure status is confirmed in the gate driver, but I can't tell you how to confirm it. Is not it.
  • +1
    TI__Mastermind 27766 points

    Hi NY,

    A GDF occurs if a MOSFET is unable to switch on or off by the end of the tDRIVE time. This type of fault is a latched fault, so in order to clear this fault it is necessary to either use an ENABLE reset pulse, write to the CLR_FLT bit (for SPI devices), power cycle the device, or put the device in sleep mode in order to reset this type of fault. If you are using the SPI device, then you can read Fault Status 1 and VGS Status 2 registers to get more information on what type of fault occurred. If it was a GDF then bits 8 and 10 of the Fault Status 1 register will be set to 1, and one of the VGS_xx bits will be set to 1 in the VGS Status 2 register to indicate which MOSFET triggered the GDF. For instance, if the high side MOSFET of phase A failed to turn on after the end of the tDRIVE time, this would cause a GDF to trigger and the VGS_HA bit in the VGS Status 2 register would be set to 1 to indicate that it was the high side of phase A that caused the GDF. 

    If a GDF occurs you will need to look to figure out what caused the MOSFET to not switch on (or off), whether it was due to an external short of the gate, whether it was due to tDRIVE or IDRIVE being too low, or whether it was due to DRV damage. You will want to figure out the cause to resolve the issue, or else the GDF may occur every time you try to spin the motor. If the issue is that the IDRIVE is set too low so that it is unable to switch on the MOSFET by the end of tDRIVE, then this can be resolved by using a higher IDRIVE setting or using a longer tDRIVE time. For information on how to select the correct IDRIVE settings, you can refer to this FAQ. If the issue is due to an external short, then the cause of the short will need to be resolved. If the issue is due to DRV damage, I have seen instances where if the IDRIVE is set too high the ringing on the gates can exceed the voltage rating of the pin causing damage to the DRV, resulting in a GDF occurring since the DRV was unable to switch the MOSFET. In this case it would be necessary to swap out the DRV and reduce the IDRIVE settings. 

    Regards,

    Anthony Lodi