dV/dt detection for active protection of power MOS transistors

The authors describe a dV/dt sensing circuit based on the variation of maximum output current value i_N across a capacitively loaded CMOS inverter. When a CMOS inverter is driven into dynamic switching on a capacitive load, the maximum current value through the inverter is shown to be a function of the slope of the input voltage. Design rules to this dV/dt sensing circuit that take into account technological constraints are introduced. Comparison between theoretical analysis and simulation results based on the SPICE program (LEVEL=2) shows good agreement. It is suggested that the proposed method can be applied either in the implementation of efficient drives for switching power devices or in their active overvoltage protection