SBAS950B October   2019  – February 2021 ADS131M08

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Timing Diagrams
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Noise Measurements
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Input ESD Protection Circuitry
      2. 8.3.2  Input Multiplexer
      3. 8.3.3  Programmable Gain Amplifier (PGA)
      4. 8.3.4  Voltage Reference
      5. 8.3.5  Clocking and Power Modes
      6. 8.3.6  ΔΣ Modulator
      7. 8.3.7  Digital Filter
        1. 8.3.7.1 Digital Filter Implementation
          1. 8.3.7.1.1 Fast-Settling Filter
          2. 8.3.7.1.2 SINC3 and SINC3 + SINC1 Filter
        2. 8.3.7.2 Digital Filter Characteristic
      8. 8.3.8  DC Block Filter
      9. 8.3.9  Internal Test Signals
      10. 8.3.10 Channel Phase Calibration
      11. 8.3.11 Calibration Registers
      12. 8.3.12 Communication Cyclic Redundancy Check (CRC)
      13. 8.3.13 Register Map CRC
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Up and Reset
        1. 8.4.1.1 Power-On Reset
        2. 8.4.1.2 SYNC/RESET Pin
        3. 8.4.1.3 RESET Command
      2. 8.4.2 Fast Startup Behavior
      3. 8.4.3 Conversion Modes
        1. 8.4.3.1 Continuous-Conversion Mode
        2. 8.4.3.2 Global-Chop Mode
      4. 8.4.4 Power Modes
      5. 8.4.5 Standby Mode
      6. 8.4.6 Current-Detect Mode
    5. 8.5 Programming
      1. 8.5.1 Interface
        1. 8.5.1.1  Chip Select (CS)
        2. 8.5.1.2  Serial Data Clock (SCLK)
        3. 8.5.1.3  Serial Data Input (DIN)
        4. 8.5.1.4  Serial Data Output (DOUT)
        5. 8.5.1.5  Data Ready (DRDY)
        6. 8.5.1.6  Conversion Synchronization or System Reset (SYNC/RESET)
        7. 8.5.1.7  SPI Communication Frames
        8. 8.5.1.8  SPI Communication Words
        9. 8.5.1.9  ADC Conversion Data
          1. 8.5.1.9.1 Collecting Data for the First Time or After a Pause in Data Collection
        10. 8.5.1.10 Commands
          1. 8.5.1.10.1 NULL (0000 0000 0000 0000)
          2. 8.5.1.10.2 RESET (0000 0000 0001 0001)
          3. 8.5.1.10.3 STANDBY (0000 0000 0010 0010)
          4. 8.5.1.10.4 WAKEUP (0000 0000 0011 0011)
          5. 8.5.1.10.5 LOCK (0000 0101 0101 0101)
          6. 8.5.1.10.6 UNLOCK (0000 0110 0110 0110)
          7. 8.5.1.10.7 RREG (101a aaaa annn nnnn)
            1. 8.5.1.10.7.1 Reading a Single Register
            2. 8.5.1.10.7.2 Reading Multiple Registers
          8. 8.5.1.10.8 WREG (011a aaaa annn nnnn)
        11. 8.5.1.11 Short SPI Frames
      2. 8.5.2 Synchronization
    6. 8.6 Registers
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Unused Inputs and Outputs
      2. 9.1.2 Antialiasing
      3. 9.1.3 Minimum Interface Connections
      4. 9.1.4 Power Metrology Applications
      5. 9.1.5 Multiple Device Configuration
      6. 9.1.6 Code Example
      7. 9.1.7 Troubleshooting
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Voltage Measurement Front-End
        2. 9.2.2.2 Current Measurement Front-End
        3. 9.2.2.3 ADC Setup
        4. 9.2.2.4 Calibration
        5. 9.2.2.5 Formulae
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 CAP Pin Behavior
    2. 10.2 Power-Supply Sequencing
    3. 10.3 Power-Supply Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.3 Application Curves

A source generator was used to provide the voltages and currents to the system. In this design, a nominal voltage of 240 V between the line and neutral, a calibration current of 10 A, and a nominal frequency of 60 Hz were used for each phase.

When the voltages and currents are applied to the system, the design outputs the cumulative active energy pulses and cumulative reactive energy pulses at a rate of 6400 pulses per kilowatt hour. This pulse output was fed into a reference meter that determined the energy percentage error based on the actual energy provided to the system and the measured energy as determined by the active and reactive energy output pulse of the system.

The current was varied from 50 mA to 100 A for the cumulative active energy error and cumulative reactive energy error testing. A phase shift of 0°, 60°, and −60° was applied between the voltage and current waveforms fed to the design for cumulative active energy testing. Based on the error from the active energy output pulse, several plots of active energy percentage error versus current were created for 0°, 60°, and –60° phase shifts. For the cumulative reactive energy error testing, a similar process was followed except that 30°, 60°, –30°, and –60° phase shifts were used, and the cumulative reactive energy error was plotted instead of the cumulative active energy error. In the cumulative active and reactive energy testing, the sum of the energy reading of each phase was tested for accuracy.

In addition to testing active energy by varying current, active energy was also tested by varying the RMS voltage from 240 V to 15 V and measuring the active energy percentage error.

The front-end was calibrated before obtaining the following results. The active energy results are within 0.1% at 0° phase shift. At 60° and –60° phase shift, which is allowed to have relaxed accuracy in electricity meter standards, the trend where the results deviate at higher currents is from the CT phase shift varying across current.

Table 9-3 shows the cumulative active energy accuracy results with changing voltage. Table 9-4 shows the cumulative active energy results with varying current. Figure 9-8 shows a plot of the values in Table 9-4.

Table 9-3 Cumulative Phase Active Energy % Error Versus Voltage, Two-Voltage Mode
VOLTAGE (V) % ERROR
240 0.0353
120 0.022
60 0.016
30 0.014
15 0.013
Table 9-4 Cumulative Phase Active Energy % Error Versus Current
CURRENT (A) 0° 60° –60°
0.05 0.019 0.045 –0.032
0.10 0.006 0.058 –0.032
0.25 0.0125 0.045 –0.0385
0.50 0.006 0.032 –0.032
1.00 0.015 0.045 –0.019
2.00 0.003 0.045 –0.039
5.00 0.006 0.024 –0.012
10.00 0.01 0.0165 0
20.00 –0.007 0.002 –0.013
30.00 0.002 –0.007 0.0085
40.00 0 –0.016 0.019
50.00 –0.003 –0.035 0.042
60.00 0.002 –0.047 0.053
70.00 0.009 –0.047 0.063
80.00. 0.007 –0.05 0.067
90.00 0.013 –0.045 0.08
100.00 0.0223 –0.04 0.092
GUID-AE8B4109-816D-43A8-B6A5-5ABAE3192996-low.gifFigure 9-8 Cumulative Phase Active Energy % Error Versus Current

Table 9-5 shows the cumulative reactive energy accuracy results with changing current. Figure 9-9 shows a plot of the values in Table 9-4.

Table 9-5 Cumulative Reactive Energy % Error Versus Current
CURRENT (A) 30° 60° –30° –60°
0.05 –0.003 0.004 –0.023 –0.027
0.10 –0.037 –0.013 0.011 –0.008
0.25 –0.067 –0.027 0.043 0.002
1.00 –0.044 –0.021 0.0415 0.011
5.00 –0.036 –0.0183 0.022 0.001
10.00 –0.03 –0.012 0.014 –0.003
20.00 –0.041 –0.026 –0.0035 –0.013
40.00 –0.01 –0.016 –0.021 –0.016
60.00 0.025 –0.0007 –0.047 –0.0247
80.00 0.041 0.0085 –0.048 –0.021
100.00 0.054 0.02 –0.044 –0.012
GUID-1918024A-A3BF-4D9E-9288-1A21CDED8ADE-low.gifFigure 9-9 Cumulative Reactive Energy % Error Versus Current