Some aspects in the design of discrete MOS-bipolar Darlington power switches

The authors examine the switching behaviour of a MOS-bipolar Darlington switch and study the influence of principal parameters in order to take them into account for the successful design of a high-performance Darlington switch. Results indicate that the power MOSFET should be selected with an adequate safe operating area (SOA), low drain-source resistance, and low gate charge factor. The bipolar transistor should have adequate SOA, low base-emitter drop, and high current gain. The drive circuit should have a low impedance and should provide a steady negative drive during the off period. While paralleling the Darlingtons, the MOSFETs and bipolar transistors should be paralleled separately, and then joined together in Darlington with minimum wire lengths or loops