Shown here is an example of how an isolated gate driver can be used. The part used here is a BM61S41RFV-CE2 gate driver. One driver is required for each power device, so an H-bridge requires four drivers. The heavy blue wires represent the DC Bus (sometimes called DC Link); this will typically be 400 to 800 V. These isolated drivers typically take the 3.3 V or 5 V logic signals from the DSP and translate them into 0 to 18 V signals for the gate of the power device. Each secondary circuit also requires its own isolated power supply, as shown. Should the customer decide to build their isolated supply, ROHM offers gate drivers with built-in controllers (BM60051FV-CE2, 52FV-CE2, and 54FV-CE2) and a power supply IC with built-in MOSFET (BD7F100HFN-LB) which may be helpful. The isolation transformer needs to have low capacitance between primary and secondary (5 pF or so). Keep in mind agency approvals of a custom isolation transformer may take months.