SLVSHO3 April   2024 DRV8235

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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 I2C Timing Requirements
    7. 6.7 Timing Diagrams
    8. 6.8 Typical Operating Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 External Components
      2. 7.3.2 Summary of Features
      3. 7.3.3 Bridge Control
      4. 7.3.4 Current Sense and Regulation (IPROPI)
        1. 7.3.4.1 Current Sensing
        2. 7.3.4.2 Current Regulation
          1. 7.3.4.2.1 Fixed Off-Time Current Regulation
          2. 7.3.4.2.2 Cycle-By-Cycle Current Regulation
      5. 7.3.5 Stall Detection
      6. 7.3.6 Motor Voltage and Speed Regulation
        1. 7.3.6.1 Internal Bridge Control
        2. 7.3.6.2 Setting Speed/Voltage Regulation Parameters
          1. 7.3.6.2.1 Speed and Voltage Set
          2. 7.3.6.2.2 Speed Scaling Factor
            1. 7.3.6.2.2.1 Target Speed Setting Example
          3. 7.3.6.2.3 Motor Resistance Inverse
          4. 7.3.6.2.4 Motor Resistance Inverse Scale
          5. 7.3.6.2.5 KMC Scaling Factor
          6. 7.3.6.2.6 KMC
          7. 7.3.6.2.7 VSNS_SEL
        3. 7.3.6.3 Soft-Start and Soft-Stop
          1. 7.3.6.3.1 TINRUSH
      7. 7.3.7 Protection Circuits
        1. 7.3.7.1 Overcurrent Protection (OCP)
        2. 7.3.7.2 Thermal Shutdown (TSD)
        3. 7.3.7.3 VM Undervoltage Lockout (VM UVLO)
        4. 7.3.7.4 Overvoltage Protection (OVP)
        5. 7.3.7.5 nFAULT Output
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Low-Power Sleep Mode
      3. 7.4.3 Fault Mode
    5. 7.5 Programming
      1. 7.5.1 I2C Communication
        1. 7.5.1.1 I2C Write
        2. 7.5.1.2 I2C Read
  9. 8 Register Map
    1. 8.1 DRV8235_STATUS Registers
    2. 8.2 DRV8235_CONFIG Registers
    3. 8.3 DRV8235_CTRL Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application: Brushed DC Motor
      1. 9.2.1 Design Requirements
      2. 9.2.2 Stall Detection
        1. 9.2.2.1 Application Description
          1. 9.2.2.1.1 Stall Detection Timing
          2. 9.2.2.1.2 Hardware Stall Threshold Selection
      3. 9.2.3 Motor Speed and Voltage Regulation Application
        1. 9.2.3.1 Tuning Parameters
          1. 9.2.3.1.1 Resistance Parameters
          2. 9.2.3.1.2 KMC and KMC_SCALE
            1. 9.2.3.1.2.1 Case I
            2. 9.2.3.1.2.2 Case II
              1. 9.2.3.1.2.2.1 Method 1: Tuning from Scratch
                1. 9.2.3.1.2.2.1.1 Tuning KMC_SCALE
                2. 9.2.3.1.2.2.1.2 Tuning KMC
              2. 9.2.3.1.2.2.2 Method 2: Using the Proportionality factor
                1. 9.2.3.1.2.2.2.1 Working Example
      4. 9.2.4 Motor Voltage
      5. 9.2.5 Motor Current
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Bulk Capacitance
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

As a working example, let ωtuned= 500 rad/s. Thus,

  • W_SCALE is chosen as 00b (16 rad/s) since 500 < 4080, the maximum value allowable by W_SCALE based on Table 7-13.
  • Let SPEED = 0x30. Thus, ωdef=48*16=768 rad/s.
  • Plugging these values into Equation 18, we have:

Equation 18. 500768=KMC_SCALEtunedKMCtuned×16324×213
  • Simplifying, we get:
Equation 19. 785.276=KMC_SCALEtunedKMCtuned
  • The final step is to choose KMC_SCALEtuned such that KMCtunedhas the highest precision within limits (0 to 255). The following table illustrates the possible choices:
Table 9-4 Selection Example for KMC_SCALE
BitKMC_SCALEtuned valueKMC_SCALEtuned / 785.276

(Actual Value)

KMCtuned

(Rounded Value)

Comment
00b24 x 287.828Avoid selecting, since low precision.
01b24 x 2915.6416Avoid selecting, since low precision.
10b24 x 212125.18125Avoid selecting, since low precision.
11b24 x 213250.36250Can seleect this value, since highest precision.