TIDUF27A February 2025 – March 2025 AMC131M03 , MSPM0G1507
- 1
- Description
- Resources
- Features
- Applications
- 6
- 1System Description
-
2System Overview
- 2.1 Block Diagram
- 2.2
Design Considerations
- 2.2.1 Voltage Measurement Analog Front End
- 2.2.2 Analog Front End for Current Measurement
- 2.2.3 XDS110 Emulator
- 2.2.4 Bluetooth? Data Transmission
- 2.2.5 Bluetooth? Connection Between Two Modules
- 2.2.6 Bluetooth? to UART Connection
- 2.2.7 Magnetic Tamper Detection With TMAG5273 Linear 3D Hall-Effect Sensor
- 2.3 Highlighted Products
- 3Hardware, Software, Testing Requirements, and Test Results
- 4Design and Documentation Support
- 5About the Author
- 6Revision History
2.2.2 Analog Front End for Current Measurement
Figure 2-3 shows that the analog front end for current inputs is different from the analog front end for the voltage inputs.
The positive and negative leads from the SHUNT sensor are connected to pins 3 and 2 of header J15 (for Phase C). Identical voltage divider circuitry is used for Phases A and B, with terminal blocks J13 and J14 being the connectors for the SHUNT terminals.
Figure 2-3 Analog Front End for Current
InputsThe analog front end for current consists of footprints for electromagnetic interference filter beads (R82, R84, and R105), and an RC low-pass filter (R83, R85, C65, C66) and C67 that functions as an anti-aliasing filter.
Equation 2 shows how to calculate the range of differential voltages fed to the current ADC channel for a given maximum current, CT turns ratio, and burden resistor value.
Assuming a shunt value of 150μΩ, the input signal to the current ADC has a voltage swing of ±21,21mV when the maximum current rating of the meter, for example 100A, is applied. This relatively low voltage, when using GAIN = 32 is well within the required Full Scale Range of ±37.5mV, see the Full-Scale Range table in the AMC131M03 3-Channel, 64-kSPS, Simultaneous-Sampling, 24-Bit, Reinforced Isolated Delta-Sigma ADC With Integrated DC/DC Converter data sheet.