JAJSHT7 August   2019 DRV5057-Q1

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      代表的な回路図
      2.      磁気応答
  4. 4 改訂履歴
  5. 5 概要 (続き)
  6. 6 Pin Configuration and Functions
    1.     Pin 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 Sensitivity Linearity
      3. 8.3.3 Operating VCC Ranges
      4. 8.3.4 Sensitivity Temperature Compensation for Magnets
      5. 8.3.5 Power-On Time
      6. 8.3.6 Hall Element Location
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Selecting the Sensitivity Option
      2. 9.1.2 Decoding a PWM
        1. 9.1.2.1 Decoding a PWM (Digital)
          1. 9.1.2.1.1 Capture and Compare Timer Interrupt
          2. 9.1.2.1.2 Oversampling and Counting With a Timer Interrupt
          3. 9.1.2.1.3 Accuracy and Resolution
        2. 9.1.2.2 Decoding a PWM (Analog)
    2. 9.2 Typical Applications
      1. 9.2.1 Full-Swing Orientation Example
        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 Half-Swing Orientation Example
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
    3. 9.3 What to Do and What Not to Do
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 ドキュメントのサポート
      1. 12.1.1 関連資料
    2. 12.2 ドキュメントの更新通知を受け取る方法
    3. 12.3 コミュニティ・リソース
    4. 12.4 商標
    5. 12.5 静電気放電に関する注意事項
    6. 12.6 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9.2.1.2 Detailed Design Procedure

Linear Hall effect sensors provide flexibility in mechanical design because many possible magnet orientations and movements produce a usable response from the sensor. Figure 18 illustrates one of the most common orientations that uses the full north to south range of the sensor and causes a close-to-linear change in magnetic flux density as the magnet moves across the sensor. Figure 19 illustrates the close-to-linear change in magnetic field present at the sensor as the magnet moves a given distance across the sensor. The usable linear region is close to but less than the length (thickness) of the magnet.

When designing a linear magnetic sensing system, always consider these three variables: the magnet, sensing distance, and the range of the sensor. Select the DRV5057-Q1 with the highest sensitivity possible based on the system distance requirements without railing the sensor PWM output. To determine the magnetic flux density the sensor receives at the various positions of the magnet, use a magnetic field calculator or simulation software, referring to magnet specifications, and testing.

Determine if the desired accuracy is met by comparing the maximum allowed duty cycle least significant bit (%DLSBmax) with the noise level (PWM jitter) of the device. Equation 3 calculates the %DLSBmax by taking into account the used length of the linear region (travel distance), the desired resolution, and the output PWM swing (within the linear duty cycle range).

Equation 3. DRV5057-Q1 drv5057-equation-4.gif

Thus, with this example (and a linear duty cycle range of 8%D to 92%D), using Equation 3 gives (92 – 8) / (10) × 0.1 = 0.84%DLSBmax. This value is larger than the 0.1%D jitter, and therefore the desired accuracy can be achieved by using Equation 2 to select a %DLSB that is equal to or less than 0.84. Then, simply calibrate the magnet position to align the sensor output along the movement path.