Mosfet-Bipolar Hybrid Darlington Power Switches - Design. Gate Drive and Protection Circdits

The hybrid darlington, comprising a power MOSFET driver and a bipolar output stage is capable of carrying large peak currents with low drive power and further,has switching times smaller than those of a bipolar darlington. This paper considers application aspects of hybrid darlington switches such as,selection of the MOSFET and the main bipolar device to achieve a given rating, requirements of the gate drive circuit and protection of the device under faults. Drive and protection circuits are presented along with results from laboratory breadboards. A novel technique for enhancing the speed of protective action in the case of short circuit faults is presented with experimental results.