ESBT/spl reg/ in industrial PFC topologies

ESBT, standing for emitter switched bipolar transistor, represents a new family of power actuators based on emitter switching topology recently introduced in the market place as both monolithic or co-packaged (hybrid) solution suitable for high voltage high switching frequency applications. Advantages and fast switching peculiarities of the emitter-switching topology are briefly treated, as well as a short description of the single-chip solution achieved through the integration of a power MOSFET inside the emitter fingers of a power bipolar transistor. Limits of traditional base current driving circuits suitable for cascade configuration are shown. In fact they are more efficient in applications with collector current nearly constant, showing significant drawbacks in applications, such as PFCs, where large variations of collector current are involved. An innovative proportional base driving circuit based on the storage time control is presented, thus ensuring an adequate saturation level in on condition and optimizing the switching losses in all load conditions. The new driver is suitable for an integrated solution. A driver prototype has been proved in the most popular converters, widely used in industrial PFC applications, with a new 1200 V/8 A monolithic ESBT/spl trade/, highlighting the benefits of using very high voltage fast switching transistors.