SLOSE54C June   2020  – July 2022 DRV8428

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
    7. 6.7 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, Off-time and Decay Modes
        1. 7.3.5.1 Mixed Decay
        2. 7.3.5.2 Smart tune Dynamic Decay
        3. 7.3.5.3 Smart tune Ripple Control
        4. 7.3.5.4 Blanking time
      6. 7.3.6 Linear Voltage Regulators
      7. 7.3.7 Logic Level, tri-level, quad-level and seven-level Pin Diagrams
        1. 7.3.7.1 EN/nFAULT Pin
      8. 7.3.8 Protection Circuits
        1. 7.3.8.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.8.2 Overcurrent Protection (OCP)
        3. 7.3.8.3 Thermal Shutdown (OTSD)
        4. 7.3.8.4 Fault Condition Summary
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode (nSLEEP = 0)
      2. 7.4.2 Disable Mode (nSLEEP = 1, EN/nFAULT = 0/Hi-Z)
      3. 7.4.3 Operating Mode (nSLEEP = 1, EN/nFAULT = 1)
      4. 7.4.4 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 Modes
        4. 8.2.2.4 Application Curves
      3. 8.2.3 Thermal Application
        1. 8.2.3.1 Power Dissipation
          1. 8.2.3.1.1 Conduction Loss
          2. 8.2.3.1.2 Switching Loss
          3. 8.2.3.1.3 Power Dissipation Due to Quiescent Current
          4. 8.2.3.1.4 Total Power Dissipation
        2. 8.2.3.2 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 Related Documentation
    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
8.2.3.1.2 Switching Loss

The power loss due to the PWM switching frequency depends on the slew rate (tSR), supply voltage, motor RMS current and the PWM switching frequency. The switching losses in each H-bridge during rise-time and fall-time are calculated as shown in Equation 4 and Equation 5.

Equation 4. PSW_RISE = 0.5 x VVM x IRMS x tRISE_PWM x fPWM
Equation 5. PSW_FALL = 0.5 x VVM x IRMS x tFALL_PWM x fPWM

Both tRISE_PWM and tFALL_PWM can be approximated as VVM/ tSR. After substituting the values of various parameters, and assuming 30-kHz PWM frequency, the switching losses in each H-bridge are calculated as shown below -

Equation 6. PSW_RISE = 0.5 x 24-V x (0.5-A / √2) x (24-V / 240 V/µs) x 30-kHz = 0.013-W
Equation 7. PSW_FALL = 0.5 x 24-V x (2-A / √2) x (24-V / 240 V/µs) x 30-kHz = 0.013-W

The total switching loss for the stepper motor driver (PSW) is calculated as twice the sum of rise-time (PSW_RISE) switching loss and fall-time (PSW_FALL) switching loss as shown below -

Equation 8. PSW = 2 x (PSW_RISE + PSW_FALL) = 2 x (0.013-W + 0.013-W) = 0.052-W
Note:

The rise-time (tRISE) and the fall-time (tFALL) are calculated based on typical values of the slew rate (tSR). This parameter is expected to change based on the supply-voltage, temperature and device to device variation.

The switching loss is directly proportional to the PWM switching frequency. The PWM frequency in an application will depend on the supply voltage, inductance of the motor coil, back emf voltage and OFF time or the ripple current (for smart tune ripple control decay mode).