Automatic load-based MOSFET segmentation for switching DC-DC converters

This paper proposes an automated approach for the optimization of the number of active segments in switching DC-DC converters with a segmented power stage. The drain-source voltage of the active power MOSFET segments is used to estimate the load current, and an automated segment controller activates an optimized number of segments. Using this approach automatically balances the switching loss and the conduction loss in the converter over the load range. The proposed concept is implemented in a prototype discrete 500 kHz boost converter, which confirms the optimized efficiency over the load range. Potential applications include high power discrete converters, where multiple power MOSFETs in parallel are already used and monolithically integrated converters, where the power MOSFET segments, drivers and control circuits are integrated on a single ASIC.