SLOSE51A June   2020  – December 2020 DRV8428E

ADVANCE INFORMATION  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1. 5.1 Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
      1. 6.5.1 Typical Characteristics
  7. 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 Bridge Control
      3. 7.3.3 Current Regulation, Off-time and Decay Modes
        1. 7.3.3.1 Mixed Decay
        2. 7.3.3.2 Smart tune Dynamic Decay
        3. 7.3.3.3 Smart tune Ripple Control
        4. 7.3.3.4 Blanking time
      4. 7.3.4 Linear Voltage Regulators
      5. 7.3.5 Logic and Seven-Level Pin Diagrams
      6. 7.3.6 Protection Circuits
        1. 7.3.6.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.6.2 Overcurrent Protection (OCP)
        3. 7.3.6.3 Thermal Shutdown (OTSD)
        4. 7.3.6.4 Fault Condition Summary
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode (nSLEEP = 0)
      2. 7.4.2 Operating Mode (nSLEEP = 1)
      3. 7.4.3 Functional Modes Summary
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Current Regulation
        2. 8.2.2.2 Power Dissipation and Thermal Calculation
          1. 8.2.2.2.1 Application Curves
    3. 8.3 Alternate Application
      1. 8.3.1 Design Requirements
      2. 8.3.2 Detailed Design Procedure
        1. 8.3.2.1 Current Regulation
          1. 8.3.2.1.1 Stepper Motor Speed
            1. 8.3.2.1.1.1 Decay Modes
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Related Links
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.1 Bulk Capacitance

Having appropriate local bulk capacitance is an important factor in motor drive system design. It is generally beneficial to have more bulk capacitance, while the disadvantages are increased cost and physical size.

The amount of local capacitance needed depends on a variety of factors, including:

  • The highest current required by the motor system
  • The power supply’s capacitance and ability to source current
  • The amount of parasitic inductance between the power supply and motor system
  • The acceptable voltage ripple
  • The type of motor used (brushed DC, brushless DC, stepper)
  • The motor braking method

The inductance between the power supply and motor drive system will limit the rate current can change from the power supply. If the local bulk capacitance is too small, the system will respond to excessive current demands or dumps from the motor with a change in voltage. When adequate bulk capacitance is used, the motor voltage remains stable and high current can be quickly supplied.

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

The voltage rating for bulk capacitors should be higher than the operating voltage, to provide margin for cases when the motor transfers energy to the supply.

GUID-6EB2B631-1277-4E41-B203-82CDBEC7359D-low.gifFigure 9-1 Example Setup of Motor Drive System With External Power Supply