SLVSEE8B November   2019  – May 2021 DRV8899-Q1

PRODUCTION DATA  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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
    8. 6.8 Typical Characteristics
  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 Mode 4: 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  Blanking Time
      8. 7.3.8  Charge Pump
      9. 7.3.9  Linear Voltage Regulators
      10. 7.3.10 Logic Level Pin Diagrams
        1. 7.3.10.1 nFAULT Pin
      11. 7.3.11 Protection Circuits
        1. 7.3.11.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.11.2 VCP Undervoltage Lockout (CPUV)
        3. 7.3.11.3 Overcurrent Protection (OCP)
          1. 7.3.11.3.1 Latched Shutdown (OCP_MODE = 0b)
          2. 7.3.11.3.2 Automatic Retry (OCP_MODE = 1b)
        4. 7.3.11.4 Open-Load Detection (OL)
        5. 7.3.11.5 Thermal Shutdown (OTSD)
          1. 7.3.11.5.1 Latched Shutdown (OTSD_MODE = 0b)
          2. 7.3.11.5.2 Automatic Recovery (OTSD_MODE = 1b)
        6. 7.3.11.6 Overtemperature Warning (OTW)
        7. 7.3.11.7 Undertemperature Warning (UTW)
        8.      
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode (nSLEEP = 0)
      2. 7.4.2 Disable Mode (nSLEEP = 1, DRVOFF = 1)
      3. 7.4.3 Operating Mode (nSLEEP = 1, DRVOFF = 0)
      4. 7.4.4 nSLEEP Reset Pulse
      5.     
    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 Slave Device
        3. 7.5.1.3 SPI for Multiple Slave Devices in Parallel Configuration
        4. 7.5.1.4 SPI for Multiple Slave Devices in Daisy Chain Configuration
    6. 7.6 Register Maps
  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
      3. 8.2.3 Application Curves
      4. 8.2.4 Thermal Application
        1. 8.2.4.1 Power Dissipation
          1. 8.2.4.1.1 Conduction Loss
          2. 8.2.4.1.2 Switching Loss
          3. 8.2.4.1.3 Power Dissipation Due to Quiescent Current
          4. 8.2.4.1.4 Total Power Dissipation
        2. 8.2.4.2 PCB Types
        3. 8.2.4.3 Thermal Parameters for HTSSOP Package
        4. 8.2.4.4 Thermal Parameters for VQFN Package
        5. 8.2.4.5 Device Junction Temperature Estimation
  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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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Current Regulation

The current through the motor windings is regulated by a PWM current-regulation circuit. When an H-bridge is enabled, current rises through the winding at a rate dependent on the DC voltage, inductance of the winding, and the magnitude of the back EMF present. When the current hits the current regulation threshold, the bridge enters a decay mode for a period of time determined by the TOFF register setting and the selected decay mode to decrease the current. After the off-time expires, the bridge is re-enabled, starting another PWM cycle.

GUID-2FCA05FC-0984-4063-8C30-033A70A4D841-low.gifFigure 7-5 Current Chopping Waveform

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. In addition, the TRQ_DAC register can further scale the reference current.

Use Equation 1 to calculate the full-scale regulation current.

Equation 1. GUID-8E08CE15-ADB5-4093-87BD-F4CF0B450B4F-low.gif

The TRQ_DAC is adjusted via the SPI register. Table 7-6 lists the current scalar value for different inputs.

Table 7-6 Torque DAC Settings
TRQ_DACCURRENT SCALAR (TRQ)
0000b100%
0001b93.75%
0010b87.5%
0011b81.25%
0100b75%
0101b68.75%
0110b62.5
0111b56.25%
1000b50%
1001b43.75%
1010b37.5%
1011b31.25%
1100b25%
1101b18.75%
1110b12.5%
1111b6.25%