TIDUF65 March   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Consideration
    3. 2.3 Highlighted Products
      1. 2.3.1 TMCS1123
      2. 2.3.2 ADS7043
      3. 2.3.3 AMC1035
      4. 2.3.4 REF2033
  9. 3System Design Theory
    1. 3.1 Hall-Effect Current Sensor Schematic Design
    2. 3.2 Analog-to-Digital Converter
      1. 3.2.1 Delta-Sigma Modulator
        1. 3.2.1.1 Common-Mode Voltage Limit
        2. 3.2.1.2 Input Filter
        3. 3.2.1.3 Interface to MCU
      2. 3.2.2 12-bit SAR ADC
        1. 3.2.2.1 Common-Mode Voltage Limit
        2. 3.2.2.2 Input Filter
        3. 3.2.2.3 Interface to MCU
    3. 3.3 Power Supply and Reference Voltage
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
    3. 4.3 Test Setup
      1. 4.3.1 Precautions
    4. 4.4 Test Results
      1. 4.4.1 DC Performance
        1. 4.4.1.1 Output Voltage Noise and ENOB After A/D Conversion
        2. 4.4.1.2 Linearity and Temperature Drift
      2. 4.4.2 AC Performance
        1. 4.4.2.1 SNR Measurement
        2. 4.4.2.2 Latency Test
      3. 4.4.3 PWM Rejection
      4. 4.4.4 Overcurrent Response
      5. 4.4.5 Adjacent Current Rejection
      6. 4.4.6 Power Supply Rejection Ratio
      7. 4.4.7 Digital Interface
  11. 5Performance Comparison with Competitor’s Device
    1. 5.1 Effective Number of Bits
    2. 5.2 Latency
    3. 5.3 PWM Rejection
  12. 6Design and Documentation Support
    1. 6.1 Design Files
      1. 6.1.1 Schematics
      2. 6.1.2 BOM
      3. 6.1.3 PCB Layout Recommendations
        1. 6.1.3.1 Layout Prints
    2. 6.2 Tools and Software
    3. 6.3 Documentation Support
    4. 6.4 Support Resources
    5. 6.5 Trademarks
  13. 7About the Author

3.2.2.2 Input Filter

The anti-aliasing input filter is also needed for ADS7043. In Figure 3-4, R30, R33, and C20 form the input filter. Likewise with the AMC1035, the resistors and capacitors can be calculated using Equation 7:

Equation 7. 1 2 π R 30 + R 33 C 20 = B W

Choose 500kHz as filter bandwidth and a 430pF differential capacitor as C20, R30 and R33 need to be 10Ω.