SLVUDF6 September   2025

 

  1.   1
  2.   Description
  3.   Get Started
  4.   Features
  5.   Applications
  6.   6
  7. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 System Description
      1. 1.3.1 Key System Specifications
      2. 1.3.2 End Equipment
      3. 1.3.3 Electricity Meter
    4. 1.4 Device Information
  8. 2Hardware
    1. 2.1 System Overview
      1. 2.1.1 Block Diagram
      2. 2.1.2 Design Considerations
        1. 2.1.2.1 Voltage Measurement - Analog Front End
        2. 2.1.2.2 Current Measurement - Analog Front End
        3. 2.1.2.3 Input Voltage
  9. 3Software
    1. 3.1 Metrology Overview
      1. 3.1.1 Metrology Formulas
      2. 3.1.2 UART for PC GUI Communication
      3. 3.1.3 Direct Memory Access (DMA)
      4. 3.1.4 ADC Setup
      5. 3.1.5 Foreground Process
      6. 3.1.6 Background Process
      7. 3.1.7 Software Function per_sample_dsp ()
      8. 3.1.8 Frequency Measurement and Cycle Tracking
      9. 3.1.9 LED Pulse Generation
  10. 4Implementation Results
    1. 4.1 Evaluation Procedure
      1. 4.1.1 Equipment Setup
      2. 4.1.2 Test Procedure
        1. 4.1.2.1 Working with the Metrology GUI
        2. 4.1.2.2 Calibration
          1. 4.1.2.2.1 Voltage and Current Offset Calibration
          2. 4.1.2.2.2 Voltage and Current Gain Calibration
          3. 4.1.2.2.3 Active Power Gain Calibration
          4. 4.1.2.2.4 Offset Calibration
          5. 4.1.2.2.5 Phase Calibration
    2. 4.2 Performance Data and Results
      1. 4.2.1 Electricity Meter Metrology Accuracy Results
  11. 5Hardware Design Files
    1. 5.1 Schematics
    2. 5.2 PCB Layouts
    3. 5.3 Bill of Materials (BOM)
  12. 6Additional Information
    1. 6.1 Trademarks
  13. 7Compliance Information
    1. 7.1 Compliance and Certifications
  14. 8Related Documentation

2.1.2.1 Voltage Measurement - Analog Front End

The nominal voltage from the mains in many regions of the world varies from 100V to 240V, so the voltage needs to be scaled down to be sensed by an ADC. Figure 2-2 shows the analog front end for the voltage scaling.

AMC-ADC-1PH-EVM Analog Front End for Voltage InputFigure 2-2 Analog Front End for Voltage Input

The analog front end for voltage input has a voltage divider network (R4, R5, R6, R8), and RC low-pass filter (R9, R11, C7, C9, and C8).

If offset calibration is not performed, the voltage-to-current crosstalk affects active energy accuracy much more than voltage accuracy when the current is low. To maximize the accuracy at lower currents, in this design the entire ADC range is not used for the voltage channel. The reduced ADC range for the voltage channels in this design still provide more than enough accuracy for measuring voltage. Equation 1 shows how to calculate the range of differential voltages fed to the voltage ADC channel for a given Mains voltage and selected voltage divider resistor values.

Equation 1. VADCSwing,Voltage= ± VRMS× 2R8R4+R5+R6+R8

Based on this formula and selected resistor values in Figure 2-2, for a main voltage of 230V, the input signal to the voltage ADC has a voltage swing of ±246mV (174mVRMS). The ±246mV voltage ranges are well within the AMC130M02's input range.