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

7.3.2 Direct PWM Input Mode

Direct PWM mode is selected by setting the PWMMODE bit in the OFF register. In direct PWM input mode, the AIN1, AIN2, BIN1, and BIN2 directly control the state of the output drivers. This allows for driving up to two brushed DC motors. The logic is shown in Table 2:

Table 2. Direct PWM Input Mode Logic

xIN1 xIN2 xOUT1 xOUT2 OPERATION
0 0 Z Z Asynchronous Fast Decay
0 1 L H Reverse Drive
1 0 H L Forward Drive
1 1 L L Slow Decay

If mixed or auto-mixed decay modes are used, they will apply to every cycle, because current change information is not available.

In direct PWM mode, the current control circuitry is still active. The full-scale VREF is set to 2.75 V. The TORQUE register may be used to scale this value, and the ISEN sense amp gain may still be set using the ISGAIN bits of the CTRL register.

DRV8711 fun_des_SLVSC40.gifFigure 7. Direct PWM Input Mode

The current through the motor windings is regulated by an adjustable fixed-off-time PWM current regulation circuit. When an H-bridge is enabled, current rises through the winding at a rate dependent on the DC voltage and inductance of the winding and the magnitude of the back EMF present. Once the current hits the current chopping threshold, the bridge disables the current for a fixed period of time, which is programmable between 500 ns and 128 µs by writing to the TOFF bits in the OFF register. After the off time expires, the bridge is re-enabled, starting another PWM cycle.

The chopping current is set by a comparator which compares the voltage across a current sense resistor connected to the xISENx pins, multiplied by the gain of the current sense amplifier, with a reference voltage. The current sense amplifier is programmable in the CTRL register. When driving in PWM mode, the chopping current is calculated as follows:

Equation 1. DRV8711 eq1_Ichop_slvsc40.gif

Where TORQUE is the setting of the TORQUE bits, and ISGAIN is the programmed gain of the ISENSE amplifiers (5, 10, 20, or 40).