SLES242H December   2009  – July 2024 DRV8412

PRODUCTION DATA  

  1.   1
  2. 1Features
  3. 2Applications
  4. 3Description
  5. 4Pin Configuration and Functions
  6. 5Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Package Heat Dissipation Ratings
    6. 5.6 Package Power Deratings (DRV8412) #GUID-2A6DB468-D895-404F-A2E6-05A442AE2834/SLES2429141
    7. 5.7 Electrical Characteristics
    8. 5.8 Typical Characteristics
  7. 6Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Error Reporting
      2. 6.3.2 Device Protection System
        1. 6.3.2.1 Bootstrap Capacitor Undervoltage Protection
        2. 6.3.2.2 Overcurrent (OC) Protection
        3. 6.3.2.3 Overtemperature Protection
        4. 6.3.2.4 Undervoltage Protection (UVP) and Power-On Reset (POR)
      3. 6.3.3 Device Reset
    4. 6.4 Device Functional Modes
  8.   Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Full Bridge Mode Operation
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Motor Voltage
          2. 7.2.1.2.2 Current Requirement of 12V Power Supply
          3. 7.2.1.2.3 Voltage of Decoupling Capacitor
          4. 7.2.1.2.4 Overcurrent Threshold
          5. 7.2.1.2.5 Sense Resistor
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Parallel Full Bridge Mode Operation
      3. 7.2.3 Stepper Motor Operation
      4. 7.2.4 TEC Driver
      5. 7.2.5 LED Lighting Driver
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Bulk Capacitance
      2. 7.3.2 Power Supplies
      3. 7.3.3 System Power-Up and Power-Down Sequence
        1. 7.3.3.1 Powering Up
        2. 7.3.3.2 Powering Down
      4. 7.3.4 System Design Recommendations
        1. 7.3.4.1 VREG Pin
        2. 7.3.4.2 VDD Pin
        3. 7.3.4.3 OTW Pin
        4. 7.3.4.4 Mode Select Pin
        5. 7.3.4.5 Parallel Mode Operation
        6. 7.3.4.6 TEC Driver Application
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 PCB Material Recommendation
        2. 7.4.1.2 Ground Plane
        3. 7.4.1.3 Decoupling Capacitor
        4. 7.4.1.4 AGND
      2. 7.4.2 Layout Example
        1. 7.4.2.1 Current Shunt Resistor
      3. 7.4.3 Thermal Considerations
        1. 7.4.3.1 DRV8412 Thermal Via Design Recommendation
  9. 7Device and Documentation Support
    1. 7.1 Receiving Notification of Documentation Updates
    2. 7.2 Support Resources
    3. 7.3 Trademarks
    4. 7.4 Electrostatic Discharge Caution
    5. 7.5 Glossary
  10. 8Revision History
  11. 9Mechanical, Packaging, and Orderable Information
7.2.1.2.5 Sense Resistor

For optimal performance, the sense resistor must be:

  • Surface-mount
  • Low inductance
  • Rated for high enough power
  • Placed closely to the motor driver

The power dissipated by the sense resistor equals IRMS2 x R. For example, if peak motor current is 3A, RMS motor current is 2A, and a 0.05Ω sense resistor is used, the resistor will dissipate 2A² × 0.05Ω = 0.2W. The power increases quickly with higher current levels.

Resistors typically have a rated power within some ambient temperature range, along with a de-rated power curve for high ambient temperatures. When a PCB is shared with other components generating heat, margin should be added. Always measure the actual sense resistor temperature in a final system, along with the power MOSFETs, as those are often the hottest components.

Because power resistors are larger and more expensive than standard resistors, use multiple standard resistors in parallel, between the sense node and ground. This distributes the current and heat dissipation.