SBAA463A january   2021  – april 2023 TMAG5170 , TMAG5170-Q1 , TMAG5170D-Q1 , TMAG5173-Q1 , TMAG5273

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Angle Measurement With One-Dimensional Sensors
    2. 1.2 Challenges of Angular Measurements
  4. 2Benefit of Multi-Axis Sensors
    1. 2.1 Simplified Mechanical Placement
    2. 2.2 Sensitivity Matching
    3. 2.3 CORDIC Angle Estimations
    4. 2.4 Tamper and Stray Field Detection
  5. 3Angular Measurement Considerations
    1. 3.1 Sensor Alignment
    2. 3.2 Sensor Calibration
    3. 3.3 Input Referred Noise
    4. 3.4 Impact of Sample Rate
  6. 4Practical Application
    1. 4.1 Push-Button Knob
      1. 4.1.1 Evaluating Design Constraints
      2. 4.1.2 Magnet Selection
      3. 4.1.3 Prototyping and Verification
    2. 4.2 Off-Axis Design
      1. 4.2.1 Sensitivity Gain Correction
      2. 4.2.2 Accuracy Verification
  7. 5Summary
  8. 6References
  9. 7Revision History

5 Summary

Three dimensional sensors, such as TMAG5170, offer the ability to determine the angular position of a magnet using a single Hall-effect sensor. This is especially powerful in systems where space is limited. To help make the device even more accessible, built-in scalability allows the user to select nearly any position by allowing the system to scale inputs to the CORDIC calculator such that they are matched.

With amplitudes of input components matched, angular calculations are simple. The non-linearity of angular measurements can be easily eliminated by ensuring that the outputs are scaled to an equivalent magnitude before running the CORDIC algorithm.

Care should always be taken to account for mechanical tolerances and errors. The finest precision will always require some additional calibration as variations in magnet rotation such as tilt, wobble, and offset that occur during assembly and manufacturing are typically impossible to predict in advance.