SLOSE48 December   2020 DRV8434A

PRODUCTION DATA  

  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
    6. 6.6 Indexer Timing Requirements
      1. 6.6.1 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Stepper Motor Driver Current Ratings
        1. 7.3.1.1 Peak Current Rating
        2. 7.3.1.2 RMS Current Rating
        3. 7.3.1.3 Full-Scale Current Rating
      2. 7.3.2 PWM Motor Drivers
      3. 7.3.3 Microstepping Indexer
      4. 7.3.4 Controlling VREF with an MCU DAC
      5. 7.3.5 Current Regulation and Decay Mode
        1. 7.3.5.1 Smart tune Ripple Control
        2. 7.3.5.2 Blanking Time
      6. 7.3.6 Charge Pump
      7. 7.3.7 Linear Voltage Regulators
      8. 7.3.8 Logic Level, tri-level and quad-level Pin Diagrams
        1. 7.3.8.1 nFAULT Pin
      9. 7.3.9 Protection Circuits
        1. 7.3.9.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.9.2 VCP Undervoltage Lockout (CPUV)
        3. 7.3.9.3 Overcurrent Protection (OCP)
        4. 7.3.9.4 Stall Detection
        5. 7.3.9.5 Open-Load Detection (OL)
        6. 7.3.9.6 Thermal Shutdown (OTSD)
        7.       Fault Condition Summary
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode (nSLEEP = 0)
      2.      43
      3. 7.4.2 Disable Mode (nSLEEP = 1, ENABLE = 0)
      4. 7.4.3 Operating Mode (nSLEEP = 1, ENABLE = Hi-Z/1)
      5. 7.4.4 nSLEEP Reset Pulse
      6.      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 Stepper Motor Speed
        2. 8.2.2.2 Current Regulation
        3. 8.2.2.3 Decay Mode
        4. 8.2.2.4 Application Curves
        5. 8.2.2.5 Thermal Application
          1. 8.2.2.5.1 Power Dissipation
          2. 8.2.2.5.2 Conduction Loss
          3. 8.2.2.5.3 Switching Loss
          4. 8.2.2.5.4 Power Dissipation Due to Quiescent Current
          5. 8.2.2.5.5 Total Power Dissipation
          6. 8.2.2.5.6 Device Junction Temperature Estimation
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 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
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.5 Current Regulation and Decay Mode

The DRV8434A operates with smart tune ripple control decay mode, which uses only slow decay during PWM current regulation. The PWM regulation current is set by a comparator which monitors the voltage across the current sense MOSFETs in parallel with the low-side power MOSFETs. The current sense MOSFETs are biased with a reference current that is the output of a current-mode sine-weighted DAC whose full-scale reference current is set by the voltage at the VREF pin.

The full-scale regulation current (IFS) can be calculated as IFS (A) = VREF (V) / KV (V/A) = VREF (V) / 1.32 (V/A).

During PWM current chopping, the H-bridge is enabled to drive a current through the motor winding until the PWM current chopping threshold is reached. Thereafter, the winding current is re-circulated by enabling both low-side MOSFETs of the H-bridge.