Theoretical study about the RBSOA of a monolithic ESBT® (emitter-switched bipolar transistor) versus the saturation level before the switching-off

One of the main strength points of the new power actuator emitter-switched bipolar transistor (ESBT®) is its excellent safe operating area: as a matter of fact the emitter-switching concept enables the driving of the bipolar transistor in a much safer way compared to the traditional base-switching one. Nevertheless, at very high current density, well above the working ones, its ruggedness decreases a little when the saturation level, just before the turn-off, is extremely low or extremely high. This paper explains that in these conditions the device switches off not exactly in emitter-switching conditions or it is not properly sized.