Power integrated circuits and their applications

The introduction of power MOSFET technology provided the necessary impetus for including power functions-up to several amperes capability, with operating voltages up to 100 V-in the monolithic Si structure. This is the result of the MOSFETs superior Si utilisation over any other topography at the stated working voltage. Full circuit protection against overloads in voltage and current with the added proviso of protection against excessive temperature can be easily accommodated. These low voltage power integrated circuits are presently found in such diverse areas of applications as: DC/DC converters; motor controllers; and automotive high side power switches-mainly as relay replacements. The favoured technology for these monolithic structures tends to be BCD (bipolar, CMOS and DMOS) either self-isolated or junction isolated-where the type of structure tends to be one of preference. When considering monolithic structures for higher voltage applications viz. up to 1000 V-a pre-requisite for operation employing 3 phase rectified mains-only two types of technology are found to be viable: (a) junction isolation; and (b) dielectric isolation. Each of these two technologies have their individual merits and drawbacks, and the author discusses them in more detail