Fast Response Control of Stepping Inductance Voltage Regulator Module

Voltage regulator modules (VRM) have stringent efficiency and transient response requirements. A stepping inductance based VRM (SI_VRM) has been proposed by other researchers with the aim of achieving fast dynamic current response under step-load conditions. However, the scheme proposed to control the SI_VRM has several problems, such as high voltage ripple under ´inductor current recovery´ condition and interruption of inductor current without any freewheeling action. In this paper, a new control scheme is proposed for the SI_VRM which can achieve fast transient response, smooth transition between different operating states, low ripple voltage both under normal and inductor current recovery conditions. The paper also investigates the requirements of the stepping inductance and its design. Simulation and experimental results are provided to confirm the expected improvements in performance