SLIA096 January   2022 DRV5021 , DRV5021-Q1 , DRV5023 , DRV5023-Q1 , DRV5032 , DRV5033 , DRV5033-Q1 , TMAG5123 , TMAG5123-Q1 , TMAG5124 , TMAG5124-Q1 , TMAG5131-Q1 , TMAG5231 , TMAG5328

 

  1.   Trademarks
  2. 1Introduction
  3. 2Design Process
    1. 2.1 Mechanical Implementation
    2. 2.2 Magnetic Implementation
    3. 2.3 Magnet Sensor Placement
    4. 2.4 Prototyping and Bench Testing
    5. 2.5 Layout
    6. 2.6 Bench Testing
    7. 2.7 Bench Results
    8. 2.8 Error Sources
      1. 2.8.1 Offsets
      2. 2.8.2 Roll, Yaw, and Pitch
      3. 2.8.3 Magnet Variation
      4. 2.8.4 Device Variation and Temperature Drift
      5. 2.8.5 External Fields
      6. 2.8.6 Nearby Material Influence
      7. 2.8.7 Bench Setup Error
  4. 3Summary

2.8.3 Magnet Variation

Magnet variation comprises physical dimensions as well as material composition. This design used a block shaped magnet and the relevant dimensions include magnet length, width, and thickness. Magnet composition can vary due to impurities, and the variation in composition corresponds to a range in remanence, Br, which directly relates to field strength.

The B221 magnet used in this document has a tolerance of ±0.004 inches for all dimensions. A typical N42 magnet like the B221 has Br of 13000 Gauss. Product specifications outlined a Br maximum of 13200 Gauss, thereby suggesting a possible tolerance of ±200 Gauss.

Figure 2-29 and Figure 2-30 show how much the BOP maximum angle can change with respect to the magnet variation.

GUID-20211229-SS0I-QKXQ-HFJR-QQJLNVTKVFN4-low.png Figure 2-29 Length and Width Tolerance Impact on BOP Maximum Angle
GUID-20211229-SS0I-ZKNX-WMP1-TNXQ29H5ZMKK-low.png Figure 2-30 Height and Remanence Tolerance Impact on BOP Maximum Angle