SBAA449B October   2020  – October 2021 TMAG5110 , TMAG5110-Q1 , TMAG5111 , TMAG5111-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Latch Response of the 2D Hall Effect
  4. 3Two Axis Sensor Consideration
    1. 3.1 Magnet Selection
      1. 3.1.1 Pole Count
      2. 3.1.2 Magnet Strength
    2. 3.2 Sensor Selection
      1. 3.2.1 Axes of Sensitivity
        1. 3.2.1.1 In-Plane Sensor Alignment
        2. 3.2.1.2 Out-Of Plane Sensor Alignment
      2. 3.2.2 Sensor Placement
        1. 3.2.2.1 On-Axis Magnetic Field
        2. 3.2.2.2 In-Plane Magnetic Field
        3. 3.2.2.3 Out-of-Plane Magnetic Field
      3. 3.2.3 Sensitivity Selection
  5. 4Optimizing for Accuracy
    1. 4.1 Optimizing Placement for Accuracy
    2. 4.2 Optimizing a Magnet for Accuracy
  6. 5Application Implementation
  7. 6Summary
  8. 7References
  9. 8Revision History

4.2 Optimizing a Magnet for Accuracy

An additional alternative to reduce error is to increase the magnet strength. With amplitude mismatch, we can expect the greatest errors to arise when the BOP & BRP thresholds are close to the peak input value. Moreover, the zero crossings always remain electrically out of phase by 90°. Therefore, the closer the BRP & BOP thresholds are relative to the zero crossing value, the better the quadrature result.

See Table 4-1 extracted from the material variation simulation. To find angle error we will find where the z-component of the magnetic field reaches 1.1 mT and the θ component reaches 2.6 mT. This is to ensure we capture the maximum sensitivity error possible.

Table 4-1 Impact of Magnet Strength on Quadrature Error

Material

BOP - Z

BOP - θ

Angle Error

Bonded Ceramic

0.57°

29.4°

1.83°

SmCo 18

0.15°

27.68°

0.53°

N35

0.12°

27.49°

0.37°