SLVSA06K October   2009  – January 2022 DRV8824

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 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 PWM Motor Drivers
      2. 7.3.2 Current Regulation
      3. 7.3.3 Decay Mode
      4. 7.3.4 Blanking Time
      5. 7.3.5 Microstepping Indexer
      6. 7.3.6 nRESET, nENBL and nSLEEP Operation
      7. 7.3.7 Protection Circuits
        1. 7.3.7.1 Overcurrent Protection (OCP)
        2. 7.3.7.2 Thermal Shutdown (TSD)
        3. 7.3.7.3 Undervoltage Lockout (UVLO)
    4. 7.4 Device Functional Modes
      1. 7.4.1 STEP/DIR Interface
      2. 7.4.2 Microstepping
  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
      3. 8.2.3 Application Curves
  9. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
    3. 9.3 Thermal Considerations
    4. 9.4 Power Dissipation
    5. 9.5 Heatsinking
  10. 10Device and Documentation Support
    1. 10.1 Community Resources
    2. 10.2 Trademarks
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RHD|28
  • PWP|28
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.2 Current Regulation

The current through the motor windings is regulated by a fixed-frequency PWM current regulation, or current chopping. When an H-bridge is enabled, current rises through the winding at a rate dependent on the DC voltage and inductance of the winding. After the current hits the current chopping threshold, the bridge disables the current until the beginning of the next PWM cycle.

In stepping motors, current regulation is used to vary the current in the two windings in a semi-sinusoidal fashion to provide smooth motion.

The PWM chopping current is set by a comparator which compares the voltage across a current sense resistor connected to the xISEN pins, multiplied by a factor of 5, with a reference voltage. The reference voltage is input from the xVREF pins.

The full-scale (100%) chopping current is calculated in Equation 1.

Equation 1. GUID-7CFC62D0-058C-4EF7-A13E-66C5053222F2-low.gif

Example:

If a 0.5-Ω sense resistor is used and the xVREF pin is 3.3 V, the full-scale (100%) chopping current will be 3.3 V / (5 × 0.5 Ω) = 1.32 A.

The reference voltage is scaled by an internal DAC that allows fractional stepping of a bipolar stepper motor, as described in Section 7.3.5.