TIDUFF8 September   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 LDC5072-Q1
      2. 2.3.2 MSPM0G3507
      3. 2.3.3 TPSM365R3
      4. 2.3.4 TLV9062
  9. 3System Design Theory
    1. 3.1 Hardware Design
      1. 3.1.1 Target PCB
      2. 3.1.2 Coil PCB
      3. 3.1.3 Signal Chain PCB
        1. 3.1.3.1 Inductive Angle Position Sensor Front-End Schematic
        2. 3.1.3.2 Differential to Single-Ended Signal Conversion
      4. 3.1.4 MSPM0G3507 Schematic Design
      5. 3.1.5 Power Supply Design
    2. 3.2 Absolute Position Calculation
    3. 3.3 Software Design
      1. 3.3.1 Angle Calculation Timing
      2. 3.3.2 Rotary Angle Error Sources and Compensation
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 PCB Overview
      2. 4.1.2 Encoder Interface
    2. 4.2 Software
    3. 4.3 Test Setup
    4. 4.4 Test Results
      1. 4.4.1 Inductive Sensor Sine and Cosine Noise Measurement
      2. 4.4.2 Absolute Angle Noise Measurement
      3. 4.4.3 Rotary Angle Accuracy Measurement
      4. 4.4.4 Impact of Air Gap on Noise, 4th Electrical Harmonics and Total Angle Accuracy
      5. 4.4.5 Power Consumption Measurement
  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
      4. 5.1.4 Altium Project Files
      5. 5.1.5 Gerber Files
      6. 5.1.6 Assembly Drawings
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5.     Trademarks
  12. 6About the Author

4.4.3 Rotary Angle Accuracy Measurement

In this section, the angle accuracy is tested when the motor is running at a constant speed of 30rpm. The host controller sends a position data request command at 16kHz frequency and collects the reference encoder and the synchronized position data time of the TIDA-010961. Then angle of the reference encoder is compared against the inductive encoder angle. The air gap is set to the default value of 0.5mm. A total of 2500 angle samples are collected over one revolution.

Figure 4-17 and Figure 4-18 show the mechanical angular error with offset and gain calibration.

TIDA-010961 Rotary Angle Accuracy Over One Mechanical Cycle With Offset and Gain Calibration at 25°C AmbientFigure 4-17 Rotary Angle Accuracy Over One Mechanical Cycle With Offset and Gain Calibration at 25°C Ambient
TIDA-010961 Rotary Angle Accuracy Over One Electrical Cycle With Offset and Gain Calibration at 25°C AmbientFigure 4-18 Rotary Angle Accuracy Over One Electrical Cycle With Offset and Gain Calibration at 25°C Ambient

For the repeatability test, the angle data is collected twice with the same calibration parameter. Figure 4-19 shows error results of two cycles with calibration. The data of cycle 1 and cycle 2 almost completely overlap, this means there is reliable repeatability of TIDA-010961.

TIDA-010961 Rotary Angle Accuracy With Offset and Gain Calibration at 25°C Ambient, Repeated Test Run Figure 4-19 Rotary Angle Accuracy With Offset and Gain Calibration at 25°C Ambient, Repeated Test Run