Control Concepts to Improve Light Load Efficiency - Optimal Number of Phases, Baby-Buck Channel, and Adaptive Bus Voltage Positioning

Light load efficiency is as important as heavy load efficiency to switching power supplies. Optimizing light-load efficiency is often conflicting with optimizing heavy-load efficiency. To increase light-load efficiency without sacrificing heavy-load efficiency, the Optimal-Number-of-Phase (ONP) control concept is proposed to optimize multi-phase converter efficiency over a wide load range. The baby-buck concept can further increase light-load efficiency. The Adaptive-Bus-Voltage-Positioning (ABVP) concept can utilize the efficiency of the two-stage conversion system over a wide load range. These concepts are particularly useful in the laptop CPU Voltage Regulator (VR) application. With use of these concepts, the VR performance is improved significantly compared with the conventional solution.

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