Fully integrated CMOS magnetic current monitor

In this paper we present a fully-integrated magnetic current monitor, which allows accurate and non-invasive current measurements in industrial apparates. The magnetic field generated by the current to be measured is sensed by a Hall device, amplified, converted into the digital domain with 9 bits of resolution and delivered to an on-board I2S serial interface. The voltage amplifier provides digitally programmable gain and offset. On-chip zener-zapping circuits are used as PROM to store the gain and offset calibration words. Two different operating ranges (20 A and 200 A full scale) are available with independent calibration coefficients. A prototype of the complete microsystem has been integrated in a conventional 0.8 μm CMOS process. Experimental results are presented.