In an ideal world, gate drivers would connect directly to MOSFET gates and the motor drive system would operate perfectly. However, the real world creates a variety of issues for motor drive designers that cause them to add extra external components between a gate driver's outputs and the external power-stage FETs. The example in Figure 1 shows that each external power MOSFET may need up to four additional components for a designer to mitigate possible FET gate drive issues. For a three-phase driver, a designer might use up to twenty-four external components between the gate driver IC and triple halfbridge FETs.
The main reasons designers add these components are to improve radiated electromagnetic interferance (EMI) performance, protect the gate driver and FETs, and eliminate unintentional FET turn-on from switching transients. Adding these components to the gate driver increases board area and bill of materials (BOM) cost in motor drive designs. TI's Smart Gate Drive features eliminate the need for these external components while helping designers meet their EMI, robustness, and performance goals.