TIDUFE3 July   2025

 

  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 Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 TPS7A03
      2. 2.3.2 REF35
      3. 2.3.3 TVS3301
      4. 2.3.4 OPA391
      5. 2.3.5 AFE881H1
      6. 2.3.6 AFE882H1
      7. 2.3.7 SN74LV8T165
      8. 2.3.8 TMUX1219
  9. 3System Design Theory
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Test Setup
    3. 4.3 Test Results
      1. 4.3.1 Linearity Tests
        1. 4.3.1.1 Linearity Tests Summary
      2. 4.3.2 Noise Tests and Current Histogram
        1. 4.3.2.1 Noise Tests and Current Histogram Summary
      3. 4.3.3 Step Response
        1. 4.3.3.1 Step Response Summary
      4. 4.3.4 Start-Up
      5. 4.3.5 MCU Current
        1. 4.3.5.1 MCU Current Summary
      6. 4.3.6 System Currents
        1. 4.3.6.1 Summary of System Currents
  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
        1. 5.1.3.1 Layout Prints
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

4.3.6 System Currents

To see which parts of the system contribute to the power consumption, the currents in different rails are measured. In 3.3V configuration, the AFE881 uses the internal voltage reference and an internal LDO to create VDD from PVDD, whereas in 1.8V configuration, an external reference voltage is used and the VDD supply is provided from the 1.8V rail of the system.

Figure 4-53 shows where on the board the currents are measured. Figure 4-54 shows that in 1.8V configuration, one more rail is measured.

TIDA-010982 Test Setup for Current Measurements: 3.3V Figure 4-53 Test Setup for Current Measurements: 3.3V
TIDA-010982 Test Setup for Current Measurements: 1.8V Figure 4-54 Test Setup for Current Measurements: 1.8V

Figure 4-55 shows the connection of major components and power rails.

TIDA-010982 Simplified Power Tree Figure 4-55 Simplified Power Tree