8.3.6.5 Gate Driver Fault (GDF)

The GHx and GLx pins are monitored such that if the voltage on the external MOSFET gate does not increase or decrease after the t_DRIVE time, a gate driver fault is detected. This fault may be encountered if the GHx or GLx pins are shorted to the PGND, SHx, or VM pins. Additionally, a gate driver fault may be encountered if the selected I_DRIVE setting is not sufficient to turn on the external MOSFET within the t_DRIVE period. After a gate drive fault is detected, all external MOSFETs are disabled and the nFAULT pin driven low. In addition, the FAULT, GDF, and corresponding VGS bits are latched high in the SPI registers. Normal operation continues (gate driver operation and the nFAULT pin is released) when the gate driver fault condition is removed and a clear faults command is issued either through the CLR_FLT bit or an ENABLE reset pulse (t_RST). On SPI devices, setting the DIS_GDF_UVLO bit high disables this protection feature.

Gate driver faults can indicate that the selected I_DRIVE or t_DRIVE settings are too low to slew the external MOSFET in the desired time. Increasing either the I_DRIVE or t_DRIVE setting can resolve gate driver faults in these cases. Alternatively, if a gate-to-source short occurs on the external MOSFET, a gate driver fault is reported because of the MOSFET gate not turning on.