Giant Magneto Resistive (GMR) Effect Based Current Sensing Technique for Low Voltage/High Current Voltage Regulator Modules

Current sensing is one of the important functions in a dc-dc converter. It may be used for implementing current mode control or for achieving current sharing in a paralleled converters. Many current sensing schemes have been reported in literature, but they are either lossy or they require precise knowledge of the component value. In this paper, a giant magneto resistive effect based sensor is used for low voltage, high current voltage regulator module type applications. Since the current sensing is based on magnetic field, the sensing accuracy depends upon the placement of sensor on the conductor. Optimum distance is obtained for sensing the current with desired accuracy. It also gives the optimum location of the sensor to minimize the interference from closely lying current carrying conductors. Finally the performance of the sensor is experimentally verified on a 1 V/15 A buck converter switching at 1 MHz.