A Current-Sensing Method for Integrated Transformer

Current-sensing circuit is critical for dc-dc converter to achieve current mode control, current protection, and current sharing. Moreover, for voltage regulator module (VRM) applications, the inductor current needs to be sensed for adaptive voltage positioning. A high-frequency, self-driven full-bridge-type VRM has been recently proposed for high efficiency with integrated transformer. However, the existing current-sensing methods are unsuitable for integrated transformer. To solve this problem, this letter proposes a novel current-sensing method for VRMs with integrated transformer. A well-designed capacitor-resistor-sensing network is employed in parallel with the transformer´s secondary side, and then the voltage across the capacitor is sensed to monitor the transformer magnetizing inductor current instantaneously. This method is accurate, lossless, and simple in structure. A 1.2-V/130-A output voltage regulator module is built in the laboratory to verify the proposed method.