High cost, EMI issue
ADuM110+, ADuM5020
To take full advantage of a GaN transistor, the preferred requirements for isolated gate drivers are:
Maximum allowable gate voltage 7 V 100 kV/ms dv/dt at switching node, 100 kV/µs to 200 kV/µs CMTI
High-low switch delay match ≤50 ns for 650 V application
Negative voltage clamp (–3 V) for turning offThere are several solutions to drive both the high-side and low-side of the half-bridge transistor. One myth about the traditional, level-shifted, high voltage driver is that the simplest single-chip implementation is widely used only for silicon-based MOSFETs. In some high end products (for example, power supply for servers), the ADuM4223 dual-isolated driver is used to drive an MOS for compact designs. However, when turning to GaN, the level-shift solution has disadvantages, such as very large propagation delay and limited common-mode transient immunity (CMTI) and is not optimal for high switching frequency. The dual-isolated d