SLVSH03 December   2023 DRV8234

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
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Timing Requirements
    7. 6.7 Timing Diagrams
    8. 6.8 Typical Operating Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 External Components
      2. 7.3.2 Summary of Features
      3. 7.3.3 Bridge Control
      4. 7.3.4 Current Sense and Regulation (IPROPI)
        1. 7.3.4.1 Current Sensing
        2. 7.3.4.2 Current Regulation
          1. 7.3.4.2.1 Fixed Off-Time Current Regulation
          2. 7.3.4.2.2 Cycle-By-Cycle Current Regulation
      5. 7.3.5 Stall Detection
      6. 7.3.6 Ripple Counting
        1. 7.3.6.1 Ripple Counting Parameters
          1. 7.3.6.1.1  Motor Resistance Inverse
          2. 7.3.6.1.2  Motor Resistance Inverse Scale
          3. 7.3.6.1.3  KMC Scaling Factor
          4. 7.3.6.1.4  KMC
          5. 7.3.6.1.5  Filter Damping Constant
          6. 7.3.6.1.6  Filter Input Scaling Factor
          7. 7.3.6.1.7  Ripple Count Threshold
          8. 7.3.6.1.8  Ripple Count Threshold Scale
          9. 7.3.6.1.9  T_MECH_FLT
          10. 7.3.6.1.10 VSNS_SEL
          11. 7.3.6.1.11 Error Correction
            1. 7.3.6.1.11.1 EC_FALSE_PER
            2. 7.3.6.1.11.2 EC_MISS_PER
        2. 7.3.6.2 RC_OUT Output
        3. 7.3.6.3 Ripple Counting with nFAULT
      7. 7.3.7 Motor Voltage and Speed Regulation
        1. 7.3.7.1 Internal Bridge Control
        2. 7.3.7.2 Setting Speed/Voltage Regulation Parameters
          1. 7.3.7.2.1 Speed and Voltage Set
          2. 7.3.7.2.2 Speed Scaling Factor
        3. 7.3.7.3 Soft-Start and Soft-Stop
          1. 7.3.7.3.1 TINRUSH
      8. 7.3.8 Protection Circuits
        1. 7.3.8.1 Overcurrent Protection (OCP)
        2. 7.3.8.2 Thermal Shutdown (TSD)
        3. 7.3.8.3 VM Undervoltage Lockout (VM UVLO)
        4. 7.3.8.4 Overvoltage Protection (OVP)
        5. 7.3.8.5 nFAULT Output
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Low-Power Sleep Mode
      3. 7.4.3 Fault Mode
    5. 7.5 Programming
      1. 7.5.1 I2C Communication
        1. 7.5.1.1 I2C Write
        2. 7.5.1.2 I2C Read
    6. 7.6 Register Map
      1. 7.6.1 DRV8234_STATUS Registers
      2. 7.6.2 DRV8234_CONFIG Registers
      3. 7.6.3 DRV8234_CTRL Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application: Brushed DC Motor
      1. 8.2.1 Design Requirements
      2. 8.2.2 Stall Detection
        1. 8.2.2.1 Application Description
          1. 8.2.2.1.1 Stall Detection Timing
          2. 8.2.2.1.2 Hardware Stall Threshold Selection
      3. 8.2.3 Ripple Counting Application
        1. 8.2.3.1 Tuning Ripple Counting Parameters
          1. 8.2.3.1.1 Resistance Parameters
          2. 8.2.3.1.2 KMC and KMC_SCALE
            1. 8.2.3.1.2.1 Case I
            2. 8.2.3.1.2.2 Case II
              1. 8.2.3.1.2.2.1 Method 1: Tuning from Scratch
                1. 8.2.3.1.2.2.1.1 Tuning KMC_SCALE
                2. 8.2.3.1.2.2.1.2 Tuning KMC
              2. 8.2.3.1.2.2.2 Method 2: Using the Proportionality factor
                1. 8.2.3.1.2.2.2.1 Working Example
          3. 8.2.3.1.3 Advanced Parameters
            1. 8.2.3.1.3.1 Filter Constants
              1. 8.2.3.1.3.1.1 FLT_GAIN_SEL
              2. 8.2.3.1.3.1.2 FLT_K
            2. 8.2.3.1.3.2 T_MECH_FLT
            3. 8.2.3.1.3.3 VSNS_SEL
            4. 8.2.3.1.3.4 Additional Error Corrector Parameters
              1. 8.2.3.1.3.4.1 EC_FALSE_PER
              2. 8.2.3.1.3.4.2 EC_MISS_PER
      4. 8.2.4 Motor Voltage
      5. 8.2.5 Motor Current
      6. 8.2.6 Application Curves
  10. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  11. 10Layout
    1. 10.1 Layout Guidelines
  12. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  13. 12Revision History

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. Having more bulk capacitance is generally beneficial, 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 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 limits how the rate 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. 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.

GUID-CFF3CE3F-35BC-4C09-83C3-C9233EF66041-low.gifFigure 9-1 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.