Light Load Efficiency Improvement for Laptop VRs

Extending battery life is a big challenge for today's laptop computer, and light load efficiency is very important for battery life extension. In this paper, a novel non-linear inductor is proposed to improve DCM efficiency for laptop CPU VR. The control method with a thorough analysis is proposed for the non-linear inductor to achieve high efficiency, required output voltage ripple and transient response. Adaptive on time control is then proposed to achieve higher efficiency when Buck is running at CCM. Finally, two-stage power architecture is proposed to achieve higher efficiency within the whole CPU load range keeping the similar cost. All of the above methods are verified by experimental results.