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

4.3.2.1 Noise Tests and Current Histogram Summary

Table 4-3 shows the calculated results from the raw data in Figure 4-18 through Figure 4-26.

Table 4-3 Noise Summary
AFESUPPLY (V)DAC SETTINGMINIMUM CURRENT (mA)AVERAGE CURRENT (mA)MAXIMUM CURRENT (mA)PEAK-TO-PEAK NOISE (µA)RMS NOISE (nA)NOISE-FREE BITS (NFB)EFFECTIVE NUMBER OF BITS (ENOB)
AFE881

1.8

0

2.99452.99562.99662.0524715.618.6
AFE8811.83276813.983613.984613.98582.1925015.518.6
AFE8811.86553524.973424.974524.97572.2528915.418.4
AFE8813.302.99202.99302.99422.1516015.519.3
AFE8813.33276813.974413.975413.97642.0417315.619.1
AFE8813.36553524.959524.960624.96212.6223915.218.7
AFE8823.303.04553.04643.04731.7618415.819.1
AFE8823.33276813.501613.502413.50351.8117315.819.1
AFE8823.36553523.958023.959223.96062.624115.218.7

Overall, the histogram plots show the expected Gaussian distribution for this type of signal without any oscillation or otherwise disturbed signal. This also proves, the peak currents drawn by the MCU when waking up are not seen on the loop and are regulated properly. There is no performance difference between a 1.8V and 3.3V signal chain.