SLVSH03 December   2023 DRV8234

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 Ripple Counting
        1. 7.3.6.1 Ripple Counting Parameters
          1. 7.3.6.1.1  Motor Resistance Inverse
          2. 7.3.6.1.2  Motor Resistance Inverse Scale
          3. 7.3.6.1.3  KMC Scaling Factor
          4. 7.3.6.1.4  KMC
          5. 7.3.6.1.5  Filter Damping Constant
          6. 7.3.6.1.6  Filter Input Scaling Factor
          7. 7.3.6.1.7  Ripple Count Threshold
          8. 7.3.6.1.8  Ripple Count Threshold Scale
          9. 7.3.6.1.9  T_MECH_FLT
          10. 7.3.6.1.10 VSNS_SEL
          11. 7.3.6.1.11 Error Correction
            1. 7.3.6.1.11.1 EC_FALSE_PER
            2. 7.3.6.1.11.2 EC_MISS_PER
        2. 7.3.6.2 RC_OUT Output
        3. 7.3.6.3 Ripple Counting with nFAULT
      7. 7.3.7 Motor Voltage and Speed Regulation
        1. 7.3.7.1 Internal Bridge Control
        2. 7.3.7.2 Setting Speed/Voltage Regulation Parameters
          1. 7.3.7.2.1 Speed and Voltage Set
          2. 7.3.7.2.2 Speed Scaling Factor
        3. 7.3.7.3 Soft-Start and Soft-Stop
          1. 7.3.7.3.1 TINRUSH
      8. 7.3.8 Protection Circuits
        1. 7.3.8.1 Overcurrent Protection (OCP)
        2. 7.3.8.2 Thermal Shutdown (TSD)
        3. 7.3.8.3 VM Undervoltage Lockout (VM UVLO)
        4. 7.3.8.4 Overvoltage Protection (OVP)
        5. 7.3.8.5 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
    6. 7.6 Register Map
      1. 7.6.1 DRV8234_STATUS Registers
      2. 7.6.2 DRV8234_CONFIG Registers
      3. 7.6.3 DRV8234_CTRL Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application: Brushed DC Motor
      1. 8.2.1 Design Requirements
      2. 8.2.2 Stall Detection
        1. 8.2.2.1 Application Description
          1. 8.2.2.1.1 Stall Detection Timing
          2. 8.2.2.1.2 Hardware Stall Threshold Selection
      3. 8.2.3 Ripple Counting Application
        1. 8.2.3.1 Tuning Ripple Counting Parameters
          1. 8.2.3.1.1 Resistance Parameters
          2. 8.2.3.1.2 KMC and KMC_SCALE
            1. 8.2.3.1.2.1 Case I
            2. 8.2.3.1.2.2 Case II
              1. 8.2.3.1.2.2.1 Method 1: Tuning from Scratch
                1. 8.2.3.1.2.2.1.1 Tuning KMC_SCALE
                2. 8.2.3.1.2.2.1.2 Tuning KMC
              2. 8.2.3.1.2.2.2 Method 2: Using the Proportionality factor
                1. 8.2.3.1.2.2.2.1 Working Example
          3. 8.2.3.1.3 Advanced Parameters
            1. 8.2.3.1.3.1 Filter Constants
              1. 8.2.3.1.3.1.1 FLT_GAIN_SEL
              2. 8.2.3.1.3.1.2 FLT_K
            2. 8.2.3.1.3.2 T_MECH_FLT
            3. 8.2.3.1.3.3 VSNS_SEL
            4. 8.2.3.1.3.4 Additional Error Corrector Parameters
              1. 8.2.3.1.3.4.1 EC_FALSE_PER
              2. 8.2.3.1.3.4.2 EC_MISS_PER
      4. 8.2.4 Motor Voltage
      5. 8.2.5 Motor Current
      6. 8.2.6 Application Curves
  10. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  11. 10Layout
    1. 10.1 Layout Guidelines
  12. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  13. 12Revision History

Package Options

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

7.3.7.3 Soft-Start and Soft-Stop

The DRV8234 integrates a soft-start and stop feature to safeguard the device from high inrush currents during start up. This feature can be activated by setting the EN_SS bit to 1b when the REG_CTRL register is set to 10b (Speed Regulation) or 11b (Voltage Regulation). If speed or voltage regulation modes are inactive, the EN_SS bit has no influence on the device performance.

Soft-start comes into effect during motor start up. The motor current is slowly ramped up to the current value corresponding to the target speed over the duration of tINRUSH time. The inrush time tINRUSH can be set by the user via the 16-bit TINRUSH register. During this time tINRUSH, the FETs are internally PWMed with a duty cycle generated using the PI control loop.

Soft-stop results in a slow ramp down of motor current in time tINRUSH. This can be triggered by the following methods:

  1. The direction of rotation is changed on-the-fly. The soft stop function prevents a high current build-up through the motor windings by ramping down the current slowly and performing soft-start on the other direction.
  2. Setting I2C_EN_IN1 and I2C_PH_IN2 to 0. Please note that this method sets outputs to Hi-Z after triggering soft stop, which deviates from conventional device operation where setting inputs to 0 causes the device to immediately go Hi-Z and enter coast mode.
  3. Set WSET_VSET to 0x00.

A reference block diagram containing the PI loop can be found in Section 7.3.7. Figure 7-16 shows the motor current slow ramp up at start up and ramp down at motor stop within time tINRUSH.

GUID-20231004-SS0I-G30D-6KWP-TD95Z5MRGXXJ-low.svgFigure 7-16 Soft Start and Soft Stop