TIDUEZ0A March 2021 – March 2022 TMS320F28P550SJ , TMS320F28P559SJ-Q1
Unlike the Si power boards which are driven by isolated gate drivers as explained in Section 2.2.8, the TI GaN device LMG3422R030 has built-in gate drive. So the power stage needs signal isolation to interface with the MCU. Figure 2-9 shows the GaN power stage. The ISO7741 isolator used to isolate the PWM input has another channel in the reverse direction that can transmit the fault signal back to the MCU side. As this is a negative logic one, an AND gate is used to combine these signals to give a negative logic fault signal back to the MCU if either of these GaN devices generate a fault.