SLVSAX9G September   2011  – November 2025 DRV8818

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Motor Driver Timing Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 PWM H-Bridge Drivers
      2. 6.3.2 Current Regulation
      3. 6.3.3 Decay Mode
      4. 6.3.4 Microstepping Indexer
      5. 6.3.5 Protection Circuits
        1. 6.3.5.1 Overcurrent Protection (OCP)
        2. 6.3.5.2 Thermal Shutdown (TSD)
        3. 6.3.5.3 Undervoltage Lockout (UVLO)
    4. 6.4 Device Functional Modes
      1. 6.4.1 Sleep Mode
      2. 6.4.2 Disable Mode
      3. 6.4.3 Active Mode
      4. 6.4.4 Decay Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Stepper Motor Speed
        2. 7.2.2.2 Current Regulation
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Bulk Capacitance
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Heatsinking
      2. 7.4.2 Layout Example
      3. 7.4.3 Thermal Considerations
        1. 7.4.3.1 Power Dissipation
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.4.4 Decay Modes

The DRV8818 supports three different decay modes: slow decay, fast decay, and mixed decay. The current through the motor windings is regulated using a fixed off time scheme.

This means that the current increases until reaching the current chopping threshold (ITRIP), after which the current enters the set decay mode for a fixed period of time. The cycle then repeats after the decay period expires.

The blanking time tBLANK defines the minimum drive time for the current chopping. ITRIP is ignored during tBLANK, so the winding current can overshoot the trip level.