The gate drive current strength, IDRIVE, is selected based on the gate-to-drain charge of the external MOSFETs and the target rise and fall times at the outputs. If IDRIVE is selected to be too low for a given MOSFET, then the MOSFET may not turn on completely within the tDRIVE time and a gate drive fault may be asserted. Additionally, slow rise and fall times will lead to higher switching power losses. TI recommends adjusting these values in system with the required external MOSFETs and motor to determine the best possible setting for any application.
The IDRIVEP and IDRIVEN current for both the low-side and high-side MOSFETs are independently adjustable on SPI devices through the SPI registers. On hardware interface devices, both source and sink settings are selected at the same time on the IDRIVE pin.