STMicroelectronics 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 the signal-to-noise ratio for optimal accuracy.
The STMicroelectronics ISOSD61 outputs the current sigma-delta bitstreams and oversamples the signal using a clock (up to 15MHz) distributed synchronized by the microcontroller. 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 calibrate the board.
