87% Overall High Efficiency and 11 mu A Ultra-Low Standby Current Derived by Overall Power Management in Laptops With Flexible Voltage Scaling and Dynamic Voltage Scaling Techniques

Abstract

The proposed overall power management in laptops can improve overall power conversion efficiency by the flexible voltage scaling (FVS) technique in cooperation with conventional dynamic voltage scaling (DVS) technique. The FVS technique separates the controller into two parts. One is a simple primary side controller and the other is emerged into the power management unit in the laptop for getting direct power control from the microprocessor. 12% light load efficiency and 7% peak efficiency are improved compared to conventional design with the DVS technique only but without the FVS technique. Furthermore, green mode is proposed to effectively reduce chip quiescent current to 11 mu A and to suppress power loss to 10 m W in ultra-light load, which is much smaller than 500 mW standby power defined by the restriction of Energy Star Standard and 40 mW of state-of-art commercial products.