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

8.2.2.4 Pick Decay Mode

The DRV8711 supports three different decay modes: slow decay, fast decay, and mixed decay. The DRV8711 also supports automatic mixed decay mode, which minimizes current ripple. The current through the motor windings is regulated using programmable settings for blanking, decay and off time. This means that after any drive phase, when a motor winding current has hit the current chopping threshold (ITRIP), the DRV8711 will place the winding in the programmed decay modes until the cycle has expired. Afterward, a new drive phase starts.

If there is a desired PWM chopping frequency, ƒPWM, use Equation 12. Note that this will only ensure that the minimum PWM frequency is ƒPWM, since the drive time may be longer than TBLANK.

Equation 12. TBLANK + TOFF + (2 × DTIME) ≈ 1/ƒPWM (Hz)

If there is no target ƒPWM, the best way to choose TBLANK and TOFF is to tune the DRV8711 in-system based on the chosen decay mode.

In most applications, it is recommended to use auto mixed decay. This decay mode eliminates some of the disadvantages of the other decay modes when the motor is stopped.

TOFF defines the time that the device is in the defined decay mode.

OFF Register Address = 0x02h
Bit Name Size R/W Default Description
7-0 TOFF 8 R/W 0x30h Sets fixed off time, in increments of 500 ns
0x00h: 500 ns
0xFFh: 128 µs

TBLANK defines the minimum drive time for the PWM current chopping. ITRIP is ignored during TBLANK, so the winding current may overshoot the trip level. In auto mixed decay, TBLANK also sets the fast decay time.

BLANK Register Address = 0x00h
Bit Name Size R/W Default Description
7-0 TBLANK 8 R/W 0x80h Sets current trip blanking time, in increments of 20ns
0x00h: 1.00 µs
…
0x32h: 1.00 µs
0x33h: 1.02 µs
…
0xFEh: 5.10 µs
0xFFh: 5.12 µs

If the application requires a high degree of microstepping (nm = 64, 128, or 256), it is recommended to set the ABT bit. This enables adaptive blanking time, which will cut the blanking time in half for small current steps. Adaptive blanking time allows for more accurate current control at these lower current steps.

BLANK Register Address = 0x03h
Bit Name Size R/W Default Description
8 ABT 1 R/W 0 0: Disable adaptive blanking time
1: Enable adaptive blanking time

During microstepping, current can be either increasing or decreasing from one step to the next. Fast decay can be very useful when ITRIP is decreasing, because it allows the winding current to decay very rapidly and settle at the next step. Slow decay is used often because the current decays slowly and results in a lower current ripple versus fast decay. Mixed decay and auto mixed decay allow flexibility to have the advantages of both fast decay and slow decay in the same mode.

DECAY Register Address = 0x04h
Bit Name Size R/W Default Description
10-8 DECMOD 3 R/W 001 000: Force slow decay at all times
001: Slow decay for increasing current, mixed decay for decreasing current (indexer mode only)
010: Force fast decay at all times
011: Use mixed decay at all times
100: Slow decay for increasing current, auto mixed decay for decreasing current (indexer mode only)
101: Use auto mixed decay at all times