SLVSDC7F April   2017  – February 2022 DRV5032

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Magnetic Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Magnetic Flux Direction
      2. 8.3.2 Device Version Comparison
        1. 8.3.2.1 Magnetic Threshold
        2. 8.3.2.2 Magnetic Response
        3. 8.3.2.3 Output Type
        4. 8.3.2.4 Sampling Rate
      3. 8.3.3 Hall Element Location
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Output Type Tradeoffs
    2. 9.2 Typical Applications
      1. 9.2.1 General-Purpose Magnet Sensing
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Three-Position Switch
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curve
    3. 9.3 Do's and Don'ts
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

9.2.1.2 Detailed Design Procedure

When designing a digital-switch magnetic sensing system, the user should consider these three variables: the magnet, sensing distance, and threshold of the sensor.

The DRV5032 device has a detection threshold specified by parameter BOP. To reliably activate the sensor, the magnet must apply greater than the maximum specified BOP. In such a system, the sensor typically detects the magnet before it has moved to the closest position. When the magnet moves away from the sensor, it must apply less than the minimum specified BRP to reliably release the sensor.

Magnets are made from various ferromagnetic materials that have trade-offs in cost, drift with temperature, absolute max temperature ratings, remanence or residual induction (Br), and coercivity (Hc). The Br and the dimensions of a magnet determine the magnetic flux density (B) it produces in 3-dimensional space. For simple magnet shapes, such as rectangular blocks and cylinders, there are simple equations that solve B at a given distance centered with the magnet.

GUID-31F5B734-7597-467A-8F16-C80AE5EB9D99-low.gif Figure 9-2 Rectangular Block and Cylinder Magnets

Use Equation 1 for the rectangular block shown in Figure 9-2:

Equation 1. B → =   B r π a r c t a n W L 2 D 4 D 2 + W 2 + L 2   - a r c t a n W L 2 D + T 4 D + T 2 + W 2 + L 2

Use Equation 2 for the cylinder shown in Figure 9-2:

Equation 2. B → =   B r 2 D + T 0.5 C 2 + D + T 2   - D 0.5 C 2 + D 2

where

  • W is width.
  • L is length.
  • T is thickness (the direction of magnetization).
  • D is distance.
  • C is diameter.

An online tool that uses these formulas is located at http://www.ti.com/product/drv5033.

All magnetic materials generally have a lower Br at higher temperatures. Systems should have margin to account for this, as well as for mechanical tolerances.