SLVSHA4 June   2024 DRV8421

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings Comm
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 PWM Motor Drivers
      2. 7.3.2 Truth Tables
      3. 7.3.3 Parallel Operation
      4. 7.3.4 Protection Circuits
        1. 7.3.4.1 OCP
        2. 7.3.4.2 TSD
        3. 7.3.4.3 UVLO
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Application Curves
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Bulk Capacitance Sizing
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Community Resources
    2. 9.2 Trademarks
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.1 Bulk Capacitance Sizing

Bulk capacitance sizing is an important factor in motor drive system design. It depends on a variety of factors including:

  • Type of power supply
  • Acceptable supply voltage ripple
  • Parasitic inductance in the power supply wiring
  • Type of motor (brushed DC, brushless DC, stepper)
  • Motor startup current
  • Motor braking method

The inductance between the power supply and motor drive system limits the rate that current can change from the power supply. If the local bulk capacitance is too small, the system responds to excessive current demands or dumps from the motor with a change in voltage. Size the bulk capacitance to meet acceptable voltage ripple levels.

The data sheet provides a recommended minimum value, but system-level testing is required to determine the appropriate-sized bulk capacitor.

DRV8421 Setup of Motor Drive System With External Power SupplyFigure 8-4 Setup of Motor Drive System With External Power Supply