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It is possible then to use these high current drivers

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Unformatted text preview: on to a copper pad on a printed circuit board for better heat dissipation. It is possible then to use these high current drivers for very high frequency switching application, driving high current MOSFET modules for a high power converter/inverter. Fig. (1) shows a basic low side driver configuration. C1 is used as a bypass capacitor placed very close to pin No. 1 and 8 of the driver IC. Fig. (9) shows a method to separately control the turn on and turn off times of MOSFET/IGBT. Turn-on time can be adjusted by Rgon, while the turn-off time can be varied by R . Schotkky goff diodes facilitate this, by virtue of their very low forward voltage drop and low trr. The 18V, 400mW Zener diodes protect the Gate-Emitter junction of the IGBT. A careful layout of the PCB, making shortest possible length between output pin and IGBT Gate, while providing generous copper surface for a ground plane, helps achieve fast turn-on and turn-off times without creating oscillation in the Drain/Collector current. Fig. (9) shows another arrangement and includes a method for faster turn-off using a PNP transistor placed very close to the MOSFET Gate and Source. It is a good practice to tie the ENABLE pin of drivers to Vcc through a 10K resistor. This ensures that the driver always remains in its ENABLED mode except when driven low due to a FAULT signal. Again, this FAULT signal puts these two drivers into their TRISTATE output mode. Fig. (10) shows a method to boost output from driver IC to a much higher level for driving very high power IGBT module. Here the turn-on and turn-off times can be varied by choosing different values of resistors: Rgon and Rgoff. To provide –ve bias of 5 Volts, the IGBT emitter is grounded to the common of +15V and –5V power supply, which feeds +15V and –5 v to the IXD_408. Notice that the incoming signals must also be level shifted. Fig. (12) shows a high current driver IC driving one IGBT of a Converter Brake Inverter (CBI) module. Here all protection features are incorporated. For H...
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