Current-sensing technique for current-mode controlled voltage regulator modules

This paper introduces an innovative current-sense technique for voltage regulator modules (VRMs). The proposed method is applied to a multiphase buck converter although the converter topology does not affect the accuracy or effectiveness of the proposed technique. A RC network is parallel connected with the buck converter low-side MOSFET and the voltage signal across the sense capacitor reconstructs the inductor current waveform. The RC technique benefits from all the advantages of the most popular current-sensing technique, the inductor DC resistance current-sense method, cutting off its main disadvantage. The sense network design is oriented to obtain high immunity to noise and a great dynamic in current-mode control by properly selecting the sense signal slop during Ton and Toff time slots. A laboratory prototype of a multiphase buck converter with current-mode control implementing the proposed current-sense method is described and experimental results are shown.