drive%20mosfet

Another path chosen by some manufacturers is trench

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Unformatted text preview: ation! Another path chosen by some manufacturers is Trench IGBTs, which also have improved VCE(sat) and switching losses. current still higher. It allows one to choose different Turn-On and Turn-Off times by choosing different values of Rgon and Rgoff . It allows for incorporating – ve bias for reasons explained above. A pair of 18 V Zener diodes with their cathodes connected together protects the Gate-Emitter Junction of IGBT from voltage spikes. 2. TYPES OF DRIVERS 2.3 TECHNIQUES TO GENERATE –Ve BIAS DURING TURN-OFF 2.1 IC DRIVERS Although there are many ways to drive MOSFET/IGBTs using hard-wired electronic circuits, IC Drivers offer convenience and features that attract designers. The foremost advantage is compactness. IC Drivers intrinsically offer lower propagation delay. As all important parameters are specified in an IC Driver, designers need not go through time consuming process of defining, designing and testing circuits to drive MOSFET/IGBTs. Another advantage is repeatability and predictability of performance, which can’t be easily achieved in hardwired driver circuits. 2.2 TECHNIQUES AVAILABLE TO BOOST CURRENT OUTPUTS Totem pole stage with N-Channel and PChannel MOSFETs can be used to boost the output from an IC Driver. The disadvantage is that the signal is inverted and also there exists momentary shoot through when common gate voltage is in transition. Totem pole arrangement using matched NPNPNP transistors; on the other hand, offer many advantages, while boosting the output currents from IC Drivers. Shoot through phenomenon is absent in this case. The pair of transistors protects each other’s base-emitter junctions and handle current surges quite well. One such arrangement is shown in Fig. (10). Here Q1 is a NPN transistor, while Q2 is a matched PNP transistor with appropriate collector current rating and switching speed to satisfy Drive requirement for the High Power IGBT. Another feature added is –ve bias for guaranteed fast switch-off even in electrically n...
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This note was uploaded on 01/15/2014 for the course ECE 624 taught by Professor Staff during the Winter '08 term at Ohio State.

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