SLES242G December   2009  – December 2014 DRV8412

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Application Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Package Heat Dissipation Ratings
    6. 6.6 Package Power Deratings (DRV8412)
    7. 6.7 Electrical Characteristics
    8. 6.8 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 Error Reporting
      2. 7.3.2 Device Protection System
        1. 7.3.2.1 Bootstrap Capacitor Undervoltage Protection
        2. 7.3.2.2 Overcurrent (OC) Protection
        3. 7.3.2.3 Overtemperature Protection
        4. 7.3.2.4 Undervoltage Protection (UVP) and Power-On Reset (POR)
      3. 7.3.3 Device Reset
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Full Bridge Mode Operation
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Motor Voltage
          2. 8.2.1.2.2 Current Requirement of 12-V Power Supply
          3. 8.2.1.2.3 Voltage of Decoupling Capacitor
          4. 8.2.1.2.4 Overcurrent Threshold
          5. 8.2.1.2.5 Sense Resistor
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Parallel Full Bridge Mode Operation
      3. 8.2.3 Stepper Motor Operation
      4. 8.2.4 TEC Driver
      5. 8.2.5 LED Lighting Driver
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
    2. 9.2 Power Supplies
    3. 9.3 System Power-Up and Power-Down Sequence
      1. 9.3.1 Powering Up
      2. 9.3.2 Powering Down
    4. 9.4 System Design Recommendations
      1. 9.4.1 VREG Pin
      2. 9.4.2 VDD Pin
      3. 9.4.3 OTW Pin
      4. 9.4.4 Mode Select Pin
      5. 9.4.5 Parallel Mode Operation
      6. 9.4.6 TEC Driver Application
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 PCB Material Recommendation
      2. 10.1.2 Ground Plane
      3. 10.1.3 Decoupling Capacitor
      4. 10.1.4 AGND
    2. 10.2 Layout Example
      1. 10.2.1 Current Shunt Resistor
    3. 10.3 Thermal Considerations
      1. 10.3.1 DRV8412 Thermal Via Design Recommendation
  11. 11Device and Documentation Support
    1. 11.1 Related Links
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1.2.5 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 3 A, RMS motor current is 2 A, and a 0.05-Ω sense resistor is used, the resistor will dissipate 2 A² × 0.05 Ω = 0.2 W. 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.