TIDUF25A June   2023  – March 2025 ADS131M08 , MSPM0G1507

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 End Equipment
    2. 1.2 Electricity Meter
    3. 1.3 Power Quality Meter, Power Quality Analyzer
    4. 1.4 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 External Supply Voltage Supervisor (SVS) With TPS3840
      2. 2.2.2 Magnetic Tamper Detection With TMAG5273 Linear 3D Hall-Effect Sensor
      3. 2.2.3 Analog Inputs
        1. 2.2.3.1 Voltage Measurement Analog Front End
        2. 2.2.3.2 Current Measurement Analog Front End
    3. 2.3 Highlighted Products
      1. 2.3.1  ADS131M08
      2. 2.3.2  MSPM0G3507
      3. 2.3.3  MSP430FR4131 for Driving Segmented LCD Displays
      4. 2.3.4  TPS3840
      5. 2.3.5  THVD1400
      6. 2.3.6  ISO6731
      7. 2.3.7  ISO6720
      8. 2.3.8  TRS3232E
      9. 2.3.9  TPS709
      10. 2.3.10 TMAG5273
  9. 3System Design Theory
    1. 3.1  How to Implement Software for Metrology Testing
    2. 3.2  Clocking System
    3. 3.3  UART Setup for GUI Communication
    4. 3.4  Real-Time Clock (RTC)
    5. 3.5  LCD Controller in MSP430FR4131
    6. 3.6  Direct Memory Access (DMA)
    7. 3.7  ADC Setup
    8. 3.8  Foreground Process
      1. 3.8.1 Formulas
    9. 3.9  Background Process
    10. 3.10 Software Function per_sample_dsp()
      1. 3.10.1 Voltage and Current Signals
      2. 3.10.2 Frequency Measurement and Cycle Tracking
    11. 3.11 LED Pulse Generation
    12. 3.12 Phase Compensation
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Required Hardware and Software
      1. 4.1.1 Hardware
      2. 4.1.2 Cautions and Warnings
    2. 4.2 Test Setup
      1. 4.2.1  Connecting the TIDA-010243 to the Metering Test Equipment
      2. 4.2.2  Power Supply Options and Jumper Settings
      3. 4.2.3  Electricity Meter Metrology Accuracy Testing
      4. 4.2.4  Viewing Metrology Readings and Calibration
        1. 4.2.4.1 Viewing Results From LCD
        2. 4.2.4.2 Calibrating and Viewing Results From PC
      5. 4.2.5  Calibration and FLASH Settings for MSPM0+ MCU
      6. 4.2.6  Gain Calibration
      7. 4.2.7  Voltage and Current Gain Calibration
      8. 4.2.8  Active Power Gain Calibration
      9. 4.2.9  Offset Calibration
      10. 4.2.10 Phase Calibration
      11. 4.2.11 Software Code Example
    3. 4.3 Test Results
      1. 4.3.1 SVS Functionality Testing
      2. 4.3.2 Electricity Meter Metrology Accuracy Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
      4. 5.1.4 Layout Prints
      5. 5.1.5 Gerber Files
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author
  13. 7Revision History

5.1.3 PCB Layout Recommendations

For this design, the following general guidelines must be followed:

  • Place decoupling capacitors close to the associated pins of the capacitors.
  • Use ground planes instead of ground traces and minimize the cuts in the ground plane, especially near the ADS131M08. In this design, there is a ground plane on both the top and bottom layer; for this situation, make sure that there is good stitching between the planes through the liberal use of vias.
  • Keep the two traces to the inputs of an ADC channel symmetrical and as close as possible to each other.
  • Crosstalk from the voltage to current channels can reduce accuracy at lower currents if power offset is not performed. To minimize voltage to current crosstalk on the PCB, assign ADC channels 0, 1, and 2 to the current channels and channels 3, 4, and 5 to the voltage channels or vice versa: ADC channels 0, 1, and 2 are the voltage channels and channels 3, 4, and 5 are the current channels.
  • For the ADS131M08 device, place the 0.1μF capacitor closest to the AVDD pin than the 1μF capacitor. Do the same thing also for the 0.1μF and 1μF capacitors connected to DVDD.
  • The order of the AINxP and AINxN pins on the ADS131M08 switches when going from one converter channel to another. This swapped order is dealt with in this design by routing the connections at J4 and J6 on the PCB accordingly.
  • Minimize the length of the traces used to connect the crystal to the microcontroller. Place guard rings around the leads of the crystal and ground the crystal housing. In addition, there must be clean ground underneath the 16.384MHz crystal and placing any traces underneath the crystal must be avoided. Also, keep high-frequency signals away from the crystal.
  • Use wide traces for power-supply connections.
  • Use a different ground plane for the isolated RS-232 and RS-485. This other ground plane is at the potential of the RS-232 and RS-485 ground and not the GND used elsewhere in the board.
  • Make sure that the recommended clearance and creepage spacing are met for the ISO6731 and ISO6720 isolation devices in this design.