SLVSGI0C September   2022  – June 2024 DRV8411

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 Timing Diagrams
  8. 7 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 External Components
    4. 8.4 Feature Description
      1. 8.4.1 Bridge Control
        1. 8.4.1.1 Parallel Bridge Interface
      2. 8.4.2 Current Regulation
      3. 8.4.3 Protection Circuits
        1. 8.4.3.1 Overcurrent Protection (OCP)
        2. 8.4.3.2 Thermal Shutdown (TSD)
        3. 8.4.3.3 Undervoltage Lockout (UVLO)
    5. 8.5 Device Functional Modes
      1. 8.5.1 Active Mode
      2. 8.5.2 Low-Power Sleep Mode
      3. 8.5.3 Fault Mode
    6. 8.6 Pin Diagrams
      1. 8.6.1 Logic-Level Inputs
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Typical Application
        1. 9.1.1.1 Stepper Motor Application
          1. 9.1.1.1.1 Design Requirements
          2. 9.1.1.1.2 Detailed Design Procedure
            1. 9.1.1.1.2.1 Stepper Motor Speed
            2. 9.1.1.1.2.2 Current Regulation
            3. 9.1.1.1.2.3 Stepping Modes
              1. 9.1.1.1.2.3.1 Full-Stepping Operation
              2. 9.1.1.1.2.3.2 Half-Stepping Operation with Fast Decay
              3. 9.1.1.1.2.3.3 Half-Stepping Operation with Slow Decay
          3. 9.1.1.1.3 Application Curves
        2. 9.1.1.2 Dual BDC Motor Application
          1. 9.1.1.2.1 Design Requirements
          2. 9.1.1.2.2 Detailed Design Procedure
            1. 9.1.1.2.2.1 Motor Voltage
            2. 9.1.1.2.2.2 Current Regulation
            3. 9.1.1.2.2.3 Sense Resistor
          3. 9.1.1.2.3 Application Curves
        3. 9.1.1.3 Thermal Considerations
          1. 9.1.1.3.1 Maximum Output Current
          2. 9.1.1.3.2 Power Dissipation
          3. 9.1.1.3.3 Thermal Performance
            1. 9.1.1.3.3.1 Steady-State Thermal Performance
            2. 9.1.1.3.3.2 Transient Thermal Performance
        4. 9.1.1.4 Multi-Sourcing with Standard Motor Driver Pinout
    2. 9.2 Power Supply Recommendations
      1. 9.2.1 Bulk Capacitance
      2. 9.2.2 Power Supply and Logic Sequencing
    3. 9.3 Layout
      1. 9.3.1 Layout Guidelines
      2. 9.3.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Community Resources
    4. 10.4 Trademarks
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.4.2 Current Regulation

The current through the motor windings may be limited, by the current regulation feature of the DRV8411. For DC motors, current control is used to limit the start-up and stall current of the motor. For stepper motors, current control is often used when the supply rail rating is higher than the motor voltage rating so the winding current remains within the motor specification.

The current regulation feature is implemented with a current chopping scheme. The PWM chopping current, ITRIP, is set by a comparator which compares the voltage across a current sense resistor connected to the xISEN pins with a reference voltage of 200 mV. Figure 8-4 shows the relevant circuitry for current regulation of a single H-bridge in DRV8411.

DRV8411 Current Regulation CircuitFigure 8-4 Current Regulation Circuit

When the motor current reaches the ITRIP level, the device enforces slow current decay by enabling both low-side FETs for a duration of tOFF as shown in Figure 8-5.

DRV8411 Current-Regulation Time PeriodsFigure 8-5 Current-Regulation Time Periods

After tOFF elapses, the output is re-enabled according to the two inputs for that bridge, xINx. The device drives current until the motor current reaches the ITRIP level again. The amount of time spent in the drive state depends on the VM voltage, the back-EMF of the motor, and the inductance of the motor. If the state of the INx control pins changes during the tOFF time, the remainder of the tOFF time is ignored, and the outputs will again follow the inputs.

After tOFF elapses, if IOUT is still greater than ITRIP, the H-bridge enters another period of brake/low-side slow decay for tOFF after a drive time of tBLANK..

The chopping current is calculated in Equation 4.

Equation 1. RSENSE = 0.2 V / ITRIP

Example: If a 1-Ω sense resistor is used, the chopping current will be 200 mV/1 Ω = 200 mA.

If current regulation is not required, the xISEN pins should be directly connected to the PCB ground plane.