EVALST-3PHISOSD Series

The EVALST-3PHISOSD evaluation board implements a complete 3-phase current meter with low-cost shunt current sensors. The solution is based on the ISOSD61 device, a single channel, galvanically isolated, second order sigma-delta modulator, measuring current for each phase through a shunt current sensor. Sensing circuitry and PCB layout are optimized to maximize signal-to-noise ratio for optimal accuracy. The ISOSD61 oversamples the signal using a clock (up to 15 MHz) distributed in a synchronized way by the microcontroller and outputs the current sigma-delta bitstreams. The firmware embedded in the solution exploits the DFSDM filters of the STM32F413RH to convert the three bitstreams into 24-bit current data, at a selectable sampling rate. The firmware also implements a virtual COM port communication to easily access the internal parameters to read data and to calibrate the board.