SLYS033 November   2021 TMAG5124-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison
  7. 6 Pin Configuration and Functions
  8. 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
      1. 7.7.1 TMAG5124A and TMAG5124E
      2. 7.7.2 TMAG5124B and TMAG5124F
      3. 7.7.3 TMAG5124C and TMAG5124G
      4. 7.7.4 TMAG5124D and TMAG5124H
      5. 7.7.5 Current Output Level
        1. 7.7.5.1 Low-Level Current Output for TMAG5124A/B/C/D
        2. 7.7.5.2 Low-Level Current Output for TMAG5124E/F/G/H
        3. 7.7.5.3 High-Level Current Output for Every Version
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Field Direction Definition
      2. 8.3.2 Device Output
      3. 8.3.3 Protection Circuits
        1. 8.3.3.1 Load Dump Protection
        2. 8.3.3.2 Reverse Polarity Protection
      4. 8.3.4 Power-On Time
      5. 8.3.5 Hall Element Location
      6. 8.3.6 Propagation Delay
      7. 8.3.7 Chopper Stabilization
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 High-Side and Low-Side Typical Application Diagrams
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
  11. 10Power Supply Recommendations
    1. 10.1 Power Derating
  12. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  13. 12Device and Documentation Support
    1. 12.1 Documentation Support
    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
  14. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.1.2 Detailed Design Procedure

When designing a digital-switch magnetic sensing system, three variables should always be considered: the magnet, sensing distance, and threshold of the sensor.

The TMAG5124 device has a detection threshold specified by parameter BOP, which is the amount of magnetic flux required to pass through the Hall sensor mounted inside the TMAG5124. To reliably activate the sensor, the magnet must apply a flux greater than the maximum specified BOP. In such a system, the sensor typically detects the magnet before it has moved to the closest position, but designing to the maximum parameter ensures robust turn-on for all possible values of BOP. 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 tradeoffs in cost, drift with temperature, absolute maximum 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-07534156-B781-4AA2-97E0-A348DFBACC7B-low.gifFigure 9-3 Rectangular Block and Cylinder Magnets

Use Equation 1 for the rectangular block shown in Figure 9-3:

Equation 1. GUID-A8CBF78D-6E87-4072-AE3E-73AEFEBB81DE-low.gif

Use Equation 2 for the cylinder shown in Figure 9-3:

Equation 2. GUID-17CE144B-4258-4F7F-8D4E-B5911BB5A7D6-low.gif

where

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

The Hall Effect Switch Magnetic Field Calculator is an online tool that uses these formulas available here: http://www.ti.com/product/tmag5124.

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.

For the TMAG5124A1, the maximum BOP is 5 mT. When choosing a 1-cm cube NdFeB N45 magnet, Equation 1 shows that this point occurs at 3 cm. This means that the magnet will activate the sensor if the design places the magnet within 3 cm from the sensor during a "turn-on" event. If the magnet is pulled away from the device, the magnetic field will go below the minimum BRP point and the device will return to its initial state.