JAJSCW7D January   2016  – November 2018 DRV8884

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図
      2.      マイクロステッピング電流の波形
  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 Indexer Timing Requirements
    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  Stepper Motor Driver Current Ratings
        1. 8.3.1.1 Peak Current Rating
        2. 8.3.1.2 RMS Current Rating
        3. 8.3.1.3 Full-Scale Current Rating
      2. 8.3.2  PWM Motor Drivers
      3. 8.3.3  Microstepping Indexer
      4. 8.3.4  Current Regulation
      5. 8.3.5  Controlling RREF With an MCU DAC
      6. 8.3.6  Decay Modes
        1. 8.3.6.1 Mode 1: Slow Decay for Increasing and Decreasing Current
        2. 8.3.6.2 Mode 2: Slow Decay for Increasing Current, Mixed Decay for Decreasing Current
        3. 8.3.6.3 Mode 3: Mixed Decay for Increasing and Decreasing Current
      7. 8.3.7  Blanking Time
      8. 8.3.8  Charge Pump
      9. 8.3.9  LDO Voltage Regulator
      10. 8.3.10 Logic and Multi-Level Pin Diagrams
      11. 8.3.11 Protection Circuits
        1. 8.3.11.1 VM UVLO
        2. 8.3.11.2 VCP Undervoltage Lockout (CPUV)
        3. 8.3.11.3 Overcurrent Protection (OCP)
        4. 8.3.11.4 Thermal Shutdown (TSD)
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Stepper Motor Speed
        2. 9.2.2.2 Current Regulation
        3. 9.2.2.3 Decay Modes
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Bulk Capacitance
  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

8.3.5 Controlling RREF With an MCU DAC

In some cases, the full-scale output current may need to be changed on the fly between many different values, depending on motor speed and loading. The RREF pin reference current can be adjusted in system by tying the RREF resistor to a DAC output instead of GND.

In this mode of operation, as the DAC voltage increases, the reference current will decrease, and therefore, the full-scale current will decrease as well. For proper operation, the output of the DAC should not rise above VRREF.

DRV8884 controlling_RREF_lvsd39.gifFigure 15. Controlling RREF With a DAC

The chopping current as controlled by a DAC is calculated as in Equation 2.

Equation 2. DRV8884 eq_01_I_FS_lvsd39.gif

Example: If a 20-kΩ resistor is connected from the RREF pin to the DAC, and the DAC is outputting 0.74 V, the chopping current will be 600 mA (TRQ at 100%).

RREF can also be adjusted using a PWM signal and low-pass filter.

DRV8884 controlling_RREFPWM_lvsd39.gifFigure 16. Controlling RREF with a PWM Resource