TIDUF25 june   2023 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

2.3.6 ISO6731

To add isolation to the RS-232 and RS-485 connection to a PC, the isolated RS-232 and isolated RS-485 portion of this reference design uses capacitive galvanic isolation, which has an inherent life span advantage over an opto-isolator. In particular, industrial devices are usually pressed into service for much longer periods of time than consumer electronics; therefore, maintenance of effective isolation over a period of 15 years or longer is important.

The ISO6731 device is a high-performance, triple-channel digital isolator designed for cost-sensitive applications requiring up to 5000 VRMS isolation ratings per UL 1577. This device is also certified by VDE, TUV, CSA, and CQC. The ISO6731 device provides high electromagnetic immunity and low emissions at low power consumption, while isolating CMOS or LVCMOS digital I/Os. Each isolation channel has a logic input and output buffer separated by TI's double capacitive silicon dioxide (SiO2) insulation barrier. This device comes with enable pins which can be used to put the respective outputs in high impedance for multi-master driving applications.

The ISO6731 device has two forward and one reverse-direction channels. In the event of input power or signal loss, the default output is high for the device without suffix F and low for the device with suffix F.

In this design, two isolation channels are used for the TX and RX in RS-485 communication mode, while the third isolation channel is used for the RE_DE control signal used to enable the receiver or driver. This chip supports a signaling rate of 50Mbps and operates from a 1.71-V to 1.89-V and 2.25-V to 5.5-V supply in the temperature range: –40°C to +125°C.