TIDUFG2 December   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Sensor Selection
    3. 2.3 Highlighted Products
      1. 2.3.1 TLV387
      2. 2.3.2 TLV9054
      3. 2.3.3 MSPM0G5187-LP
      4. 2.3.4 LOG300
      5. 2.3.5 UCC28881
      6. 2.3.6 TPS709
  9. 3System Design Theory
    1. 3.1 Current Sensor
    2. 3.2 Hybrid Integrator
    3. 3.3 Band-Pass Filter
      1. 3.3.1 Log Amplifier
      2. 3.3.2 Current Low-Pass Filter
      3. 3.3.3 Non-isolated Voltage Sensing
      4. 3.3.4 Auto Labeling Circuit
        1. 3.3.4.1 Line Voltage Sensing
        2. 3.3.4.2 Arc Gap Voltage Sensing
        3. 3.3.4.3 Differential to Single-Ended Conversion
      5. 3.3.5 Power Supply
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software
    3. 4.3 Test Setup
      1. 4.3.1 Arc Testing Setup
    4. 4.4 Test Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

4.4 Test Results

Figure 4-3 shows the transfer function of the bandpass filter from section 3.1.3. An AC input from the signal generator is injected into the input of C6 separated from the integrator output trace. The output of the bandpass filter is measured with the high bandwidth passive probe of the oscilloscope at the output of R22.


TIDA-010971 Current Band-Pass Filter Magnitude Plot

Figure 4-3 Current Band-Pass Filter Magnitude Plot

Figure 4-4 shows the band-pass output noise. This noise is less than the resolution of a 12-bit, 3.3V ADC.

TIDA-010971 Output Noise of Band-Pass Filter Figure 4-4 Output Noise of Band-Pass Filter

Figure 4-5 shows the output of the low-pass filter with a resistive load of 9.74A. The RMS voltage corresponds to Equation 4.

Equation 4. 472 m V / 9.74 A = 180 m V / A
TIDA-010971 Low-Pass Filter Output With Resistive Load Figure 4-5 Low-Pass Filter Output With Resistive Load

Figure 4-6 and Figure 4-7 show the LOG300 output for normal vs arcing for a two different loads. This demonstrates how the arcing signal reaches up to the 1MHz to 10MHz range but noise from the loads is significantly reduced. For Figure 4-6 and Figure 4-7, the top subplot shows the LOG300 output, the bottom subplot shows the oscilloscope current probe output.

TIDA-010971 Vacuum Motor Load – Top: LOG300 Bottom: Current Probe Figure 4-6 Vacuum Motor Load – Top: LOG300 Bottom: Current Probe
TIDA-010971 600W Tungsten Lamp With Dimmer Load – Top: LOG300 Bottom: Current Probe Figure 4-7 600W Tungsten Lamp With Dimmer Load – Top: LOG300 Bottom: Current Probe