Increasing The Efficiency In High Current And Low Voltage Application
The continuous quest for lower voltage and higher current has created some challenges for the power designers especially if the high efficiency and high power density is pursued. This paper will underline the challenges associated with very low voltage and high current application. It will focus mostly on the reduction of effective duty cycle due to the leakage and stray inductance. It will present a magnetic structure which actually minimizes not only the leakage inductance but also the stray inductance which plays a crucial role in this application. In addition to that the magnetic structure reduces by a factor of two the footprint of the magnetic core, using a special layout structure which leads to cancellation of the magnetic filed created by the flowing current outside of the transformer the stray inductance is practically eliminated. These concepts were implemented in a 1.2V @100A quarter brick isolated DC-DC Converter which has an efficiency 2% higher than the competition at full load and reached 90% for 1.2V @ 60A, higher than many VRMs.