High Efficiency 12V VRs with Extended Duty Cycle Concept (2001)
The conventional buck converter topology has been widely used for the 5V VRM. However, this topology is not suitable for 12V step-down DC/DC conversion because of its inherent small duty cycle, which results in poor conversion efficiency. A number of innovative topologies based on tapped inductors has been proposed and developed as shown in below. This family of new topologies can extend the duty cycle and improve the conversion efficiency. Both active or passive clamp structures have been utilized to recover the leakage-inductor energy and minimize the voltage stresses. Even more, to eliminate the switching loss and driver loss, resonant soft switching methods and lossless driving methods are being investigated.