SLVSC40H June   2013  – May 2020 DRV8711

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  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 Electrical Characteristics
    6. 6.6 SPI Timing Requirements
    7. 6.7 Indexer Timing Requirements
    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  PWM Motor Drivers
      2. 7.3.2  Direct PWM Input Mode
      3. 7.3.3  Microstepping Indexer
      4. 7.3.4  Current Regulation
      5. 7.3.5  Decay Modes
      6. 7.3.6  Blanking Time
      7. 7.3.7  Predrivers
      8. 7.3.8  Configuring Predrivers
      9. 7.3.9  External FET Selection
      10. 7.3.10 Stall Detection
        1. 7.3.10.1 Internal Stall Detection
        2. 7.3.10.2 External Stall Detection
      11. 7.3.11 Protection Circuits
        1. 7.3.11.1 Overcurrent Protection (OCP)
        2. 7.3.11.2 Predriver Fault
        3. 7.3.11.3 Thermal Shutdown (TSD)
        4. 7.3.11.4 Undervoltage Lockout (UVLO)
    4. 7.4 Device Functional Modes
      1. 7.4.1 RESET and SLEEPn Operation
      2. 7.4.2 Microstepping Drive Current
    5. 7.5 Programming
      1. 7.5.1 Serial Data Format
    6. 7.6 Register Maps
      1. 7.6.1 Control Registers
      2. 7.6.2 CTRL Register (Address = 0x00)
      3. 7.6.3 TORQUE Register (Address = 0x01)
      4. 7.6.4 OFF Register (Address = 0x02)
      5. 7.6.5 BLANK Register (Address = 0x03)
      6. 7.6.6 DECAY Register (Address = 0x04)
      7. 7.6.7 STALL Register (Address = 0x05)
      8. 7.6.8 DRIVE Register (Address = 0x06)
      9. 7.6.9 STATUS Register (Address = 0x07)
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Sense Resistor
      2. 8.1.2 Optional Series Gate Resistor
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Set Step Rate
        2. 8.2.2.2 Calculate Current Regulation
        3. 8.2.2.3 Support External FETs
        4. 8.2.2.4 Pick Decay Mode
        5. 8.2.2.5 Config Stall Detection
        6. 8.2.2.6 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community 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

7.3.10 Stall Detection

The DRV8711 implements a back EMF monitoring scheme that is capable of detecting a stall during stepper motor motion. This stall detection is intended to be used to get an indication when a motor is run into a mechanical stop, or when an increased torque load on the motor causes it to stall.

To determine that a stall has occurred, a drop in motor back EMF is detected. The DRV8711 supports two methods of this detection: an automatic internal stall detection circuit, or the ability to use an external microcontroller to monitor back EMF.

During a zero-current step, one side of the H-bridge is placed in a high impedance state, and the opposite low-side FET is turned on for a brief duration defined by TORQUE register SMPLTH bit [10:8]. This allows the current to decay quickly through the low-side FET and the opposite body diode. Which side of the bridge is tri-state and which one is driven low depends on the current direction on the previous step. The bridge with the high side that has been actively PWMed (at the beginning of the PWM cycle during blank time) before entering the zero-current step will be held low and the opposite side will be tri-stated.

Back EMF is sampled on the tri-stated output pin at the end of SMPLTH time (TORQUE register bit [10:8]). The back EMF from the selected pin is divided by 4, 8, 16, or 32, depending on the setting of the VDIV bits in the STALL register. The voltage is buffered and held on an external capacitor placed on the BEMF pin. The signal on the BEMF output pin can be further processed by a microcontroller to implement more advanced control and stall detection algorithms.

The SMPLTH bit [10] is a write-only bit. When read, the bit always reads 0. TI recommends to maintain the value of the bit locally. When a change in the TORQUE register is desired, the bit can be read locally and added to the other bits to complete the value.

DRV8711 sta_det_SLVSC40.gifFigure 15. Stall Detection