ST EVALST-3PHISOSD User Manual

UM3107
User manual
EVALST-3PHISOSD evaluation board
Introduction
The EVALST-3PHISOSD evaluation board implements a 3-phase AC/DC current meter that meets the requirements for motor
control applications using low-cost, electromagnetic-immune shunt sensors and advanced galvanic-isolation technology.
The evaluation board is based on the high-accuracy ISOSD61 Isolated Sigma-Delta Converter front-end IC, with customizable
firmware running on an STM32 microcontroller.
The ISOSD61, a single-channel second-order sigma-delta modulator, measures current for each phase through a shunt current
sensor. It oversamples the signal using a synchronized clock distributed by the microcontroller and outputs the converted
current sigma-delta bitstream. Three ISOSD61 are used in the 3-phase system to collect the current data from each phase.
Through an isolation barrier based on a thick-oxide technology, the internal digital transceiver transfers data between the
isolated domains and guarantees 6 KV VIOTM and 1.2 KV VIORM between the phases.
The firmware implemented on the STPM32F413 uses digital filters for sigma-delta modulator (DFSDM) peripheral to convert
modulated data into 24-bit current values and computes all data in real-time every 200 μs.
The firmware also implements a virtual COM port that provides access to internal parameters for reading data and calibrating
the board.
Figure 1. EVALST-3PHISOSD
UM3107 - Rev 1 - November 2022
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