SLOSE70 December   2020 DRV8434S

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 SPI Timing Requirements
    7. 6.7 Indexer Timing Requirements
      1. 6.7.1 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
      6. 7.3.6  Decay Modes
        1. 7.3.6.1 Slow Decay for Increasing and Decreasing Current
        2. 7.3.6.2 Slow Decay for Increasing Current, Mixed Decay for Decreasing Current
        3. 7.3.6.3 Slow Decay for Increasing Current, Fast Decay for Decreasing current
        4. 7.3.6.4 Mixed Decay for Increasing and Decreasing Current
        5. 7.3.6.5 Smart tune Dynamic Decay
        6. 7.3.6.6 Smart tune Ripple Control
      7. 7.3.7  PWM OFF Time
      8. 7.3.8  Blanking time
      9. 7.3.9  Charge Pump
      10. 7.3.10 Linear Voltage Regulators
      11. 7.3.11 Logic Level, tri-level and quad-level Pin Diagrams
        1. 7.3.11.1 nFAULT Pin
      12. 7.3.12 Protection Circuits
        1. 7.3.12.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.12.2 VCP Undervoltage Lockout (CPUV)
        3. 7.3.12.3 Overcurrent Protection (OCP)
          1. 7.3.12.3.1 Latched Shutdown (OCP_MODE = 0b)
          2. 7.3.12.3.2 Automatic Retry (OCP_MODE = 1b)
        4. 7.3.12.4 Stall Detection
        5. 7.3.12.5 Open-Load Detection (OL)
        6. 7.3.12.6 Overtemperature Warning (OTW)
        7. 7.3.12.7 Thermal Shutdown (OTSD)
          1. 7.3.12.7.1 Latched Shutdown (OTSD_MODE = 0b)
          2. 7.3.12.7.2 Automatic Recovery (OTSD_MODE = 1b)
        8.       Fault Condition Summary
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode (nSLEEP = 0)
      2.      56
      3. 7.4.2 Disable Mode (nSLEEP = 1, ENABLE = 0)
      4. 7.4.3 Operating Mode (nSLEEP = 1, ENABLE = 1)
      5. 7.4.4 nSLEEP Reset Pulse
      6.      Functional Modes Summary
    5. 7.5 Programming
      1. 7.5.1 Serial Peripheral Interface (SPI) Communication
        1. 7.5.1.1 SPI Format
        2. 7.5.1.2 SPI for a Single Target Device
        3. 7.5.1.3 SPI for Multiple Target Devices in Daisy Chain Configuration
        4. 7.5.1.4 SPI for Multiple Target Devices in Parallel Configuration
    6. 7.6 Register Maps
  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
      1. 10.1.1 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

8.2.2.1 Stepper Motor Speed

The first step in configuring the DRV8434S requires the desired motor speed and microstepping level. If the target application requires a constant speed, then a square wave with frequency ƒstep must be applied to the STEP pin. If the target motor speed is too high, the motor does not spin. Make sure that the motor can support the target speed. Use Equation 2 to calculate ƒstep for a desired motor speed (v), microstepping level (nm), and motor full step angle (θstep)

Equation 2. GUID-021E05D5-A80A-4753-B4BD-ADAFB242B241-low.gif

The value of θstep can be found in the stepper motor data sheet, or written on the motor. For example, the motor in this application is required to rotate at 1.8°/step for a target of 18.75 rpm at 1/8 microstep mode. Using Equation 2, ƒstep can be calculated as 500 Hz.

The microstepping level is set by the MICROSTEP_MODE bits. Higher microstepping results in a smoother motor motion and less audible noise, but requires a higher ƒstep to achieve the same motor speed.