This paper presents the design considerations for a redundant parallel multiphase voltage regulator module (VRM) system. The VRMs are modulated to achieve a controlled current source property, which helps in achieving good current sharing among modules with true redundancy. The steady-state, small-signal, and large-signal characteristics of the control are discussed. A novel local sense feedback is used to improve the large-signal dynamics of the parallel system. Two 3.3-V/140-A prototypes are used to validate the design concepts. Experimental results show good correlation with the theoretical models. The current sharing between the parallel modules is within 10%, and the dynamic voltage response improvement is 33%, as a result of the local sense feedback.
['Santanu Mishra', 'Xingsheng Zhou']
Design Considerations for a Low-Voltage High-Current Redundant Parallel Voltage Regulator Module System