SLLSEL7B October   2014  – April 2024 DRV8848

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     Pin Functions
    2.     External Components
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings Comm
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 PWM Motor Drivers
      2. 6.3.2 Bridge Control
      3. 6.3.3 Parallel Operation
      4. 6.3.4 Current Regulation
      5. 6.3.5 Current Recirculation and Decay Modes
      6. 6.3.6 Protection Circuits
        1. 6.3.6.1 OCP
        2. 6.3.6.2 TSD
        3. 6.3.6.3 UVLO
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Current Regulation
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Bulk Capacitance Sizing
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Third-Party Products Disclaimer
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
    6. 8.6 Community Resources
    7. 8.7 Trademarks
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6.3.5 Current Recirculation and Decay Modes

During PWM current chopping, the H-bridge is enabled to drive current through the motor winding until the PWM current chopping threshold is reached (see case 1 in Figure 6-3).

After the chopping current threshold is reached, the drive current is interrupted, but due to the inductive nature of the motor, current must continue to flow for some period of time. This is called recirculation current. To handle this recirculation current, the DRV8848 H-bridge operates in mixed decay mode.

Mixed decay is a combination of fast and slow decay modes. In fast decay mode, the opposite drivers are turned on to allow the current to decay (see case 2 in Figure 6-3). If the winding current approaches zero, while in fast decay, the bridge is disabled to prevent any reverse current flow. In slow decay mode, winding current is recirculated by enabling both of the low-side FETs in the bridge (see case 3 in Figure 6-3). Mixed decay starts with fast decay, then goes to slow decay. In DRV8848, the mixed decay ratio is 25% fast decay and 75% slow decay (as shown in Figure 6-4).

GUID-9F18C704-81FD-4750-8295-105D146540FD-low.gifFigure 6-3 Decay Modes
GUID-BA8F3D54-1105-4BA2-A4D5-DA8392467A41-low.gifFigure 6-4 Mixed Decay