SLVSDN2E January   2018  – March 2021 DRV10974

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 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 Speed Input and Control
      2. 7.3.2 Motor Direction Change
      3. 7.3.3 Motor-Frequency Feedback (FG)
      4. 7.3.4 Lock Detection
        1. 7.3.4.1 Lock Kt Measure
        2. 7.3.4.2 Lock No Motor
        3. 7.3.4.3 Lock Open Loop Abnormal
        4. 7.3.4.4 Lock BEMF Abnormal
        5. 7.3.4.5 Lock Closed Loop Abnormal
        6. 7.3.4.6 Lock Speed Abnormal
      5. 7.3.5 Soft Current-Limit
      6. 7.3.6 Short-Circuit Current Protection
      7. 7.3.7 Overtemperature Protection
      8. 7.3.8 Undervoltage Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Spin-Up Settings
        1. 7.4.1.1 Motor Start
        2. 7.4.1.2 Initial Speed Detect
        3. 7.4.1.3 Align
      2. 7.4.2 Open-Loop Acceleration
      3. 7.4.3 Start-Up Current Sensing
      4. 7.4.4 Closed Loop
      5. 7.4.5 Control Advance Angle
  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
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.4.4 Lock BEMF Abnormal

For any specific motor, the integrated value of BEMF during half of an electrical cycle is a constant as shown by the shaded gray area in Figure 7-9. This value is constant regardless of whether the motor runs fast or slow. The DRV10974 device monitors this value and uses it as a criterion to determine if the motor is in a lock condition.

The DRV10974 device uses the integrated BEMF to determine the Kt value of the motor during the initial motor start. Based on this measurement, a range of acceptable Kt values is established. Then, during closed-loop motor operation the Ktc (Kt calculated) value is continuously updated. Finally, the Ktc value is checked to see if it is within the range between ½ Kt and 2Kt. If the Ktc value goes beyond the acceptable range, a lock condition is triggered as shown in Figure 7-10. Note, there is a blanking period of 0.3 s after the transition from open loop to closed loop where the abnormal BEMF lock is momentarily disabled. The device uses this time to finalize the Kt value that Ktc is compared against.

GUID-87901A86-7828-44AF-A1F0-E7BAD46B6AEC-low.gifFigure 7-9 BEMF Integration
GUID-EC9410D2-722E-4D63-AAE9-3323622A0D18-low.gifFigure 7-10 Abnormal Kt Lock Detect