SLVSB19D February   2012  – March 2015 DRV8834

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  6. 6 Pin Configuration and 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 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 Current Control
      2. 8.3.2 Current Recirculation and Decay Modes
      3. 8.3.3 Protection Circuits
        1. 8.3.3.1 Overcurrent Protection (OCP)
        2. 8.3.3.2 Thermal Shutdown (TSD)
        3. 8.3.3.3 Undervoltage Lockout (UVLO)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Phase/Enable Mode
      2. 8.4.2 Indexer Mode
      3. 8.4.3 nSLEEP Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Sense Resistor
    2. 9.2 Typical Application
      1. 9.2.1 Phase/Enable Mode Driving Two DC Motors
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Motor Voltage
          2. 9.2.1.2.2 Power Dissipation
          3. 9.2.1.2.3 Motor Current Trip Point
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Phase/Enable Mode Driving a Stepper Motor
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Stepper Motor Speed
          2. 9.2.2.2.2 Current Regulation
          3. 9.2.2.2.3 Decay Modes
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Indexer Mode Driving a Stepper Motor
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedures
          1. 9.2.3.2.1 Stepper Motor Speed
          2. 9.2.3.2.2 Current Regulation
          3. 9.2.3.2.3 Decay Modes
        3. 9.2.3.3 Application Curves
      4. 9.2.4 High-Resolution Microstepping Using a Microcontroller to Modulate VREF Signals
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
        3. 9.2.4.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Bulk Capacitance
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
      1. 11.3.1 Maximum Output Current
      2. 11.3.2 Thermal Protection
      3. 11.3.3 Power Dissipation
      4. 11.3.4 Heatsinking
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

10 Power Supply Recommendations

10.1 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 capacitance of the power supply and its ability to source or sink 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.

DRV8834 example_setup_slos719.gifFigure 23. Example Setup of Motor Drive System With External Power Supply

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.