8.3.1.4.1 IDRIVE: MOSFET Slew-Rate Control

The IDRIVE component implements adjustable gate drive current to control the MOSFET V_DS slew rates. The MOSFET V_DS slew rates are a critical factor for optimizing radiated emissions, energy, and duration of diode recovery spikes, dV/dt gate turnon resulting in shoot-through, and switching voltage transients related to parasitics in the external half-bridge. The IDRIVE component operates on the principal that the MOSFET V_DS slew rates are predominately determined by the rate of gate charge (or gate current) delivered during the MOSFET Q_GD or Miller charging region. By letting the gate driver adjust the gate current, the gate driver can effectively control the slew rate of the external power MOSFETs.

The IDRIVE component lets the DRV832x family of devices dynamically switch between gate drive currents either through a register setting on SPI devices or the IDRIVE pin on hardware interface devices. The SPI devices provide 16 I_DRIVE settings ranging from 10-mA to 1-A source and 20-mA to 2-A sink. Hardware interface devices provide 7 I_DRIVE settings within the same ranges. The setting of the gate drive current is delivered to the gate during the turnon and turnoff of the external power MOSFET for the t_DRIVE duration. After the MOSFET turnon or turnoff, the gate driver switches to a smaller hold I_HOLD current to improve the gate driver efficiency. For additional details on the IDRIVE settings, see the Register Maps section for the SPI devices and the Pin Diagrams section for the hardware interface devices.