SLOSE49 November   2020 DRV8434E

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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
      1. 6.5.1 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Bridge Control
      2. 7.3.2 Current Regulation
      3. 7.3.3 Decay Modes
        1. 7.3.3.1 Mixed Decay
        2. 7.3.3.2 Fast Decay
        3. 7.3.3.3 Smart tune Dynamic Decay
        4. 7.3.3.4 Smart tune Ripple Control
        5. 7.3.3.5 Blanking time
      4. 7.3.4 Charge Pump
      5. 7.3.5 Linear Voltage Regulators
      6. 7.3.6 Logic and Quad-Level Pin Diagrams
        1. 7.3.6.1 nFAULT Pin
      7. 7.3.7 Protection Circuits
        1. 7.3.7.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.7.2 VCP Undervoltage Lockout (CPUV)
        3. 7.3.7.3 Overcurrent Protection (OCP)
        4. 7.3.7.4 Thermal Shutdown (OTSD)
        5.       Fault Condition Summary
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode (nSLEEP = 0)
      2. 7.4.2 Operating Mode (nSLEEP = 1)
      3. 7.4.3 nSLEEP Reset Pulse
      4.      Functional Modes Summary
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Current Regulation
        2. 8.2.2.2 Power Dissipation and Thermal Calculation
      3. 8.2.3 Application Curves
    3. 8.3 Alternate Application
      1. 8.3.1 Design Requirements
      2. 8.3.2 Detailed Design Procedure
        1. 8.3.2.1 Current Regulation
        2. 8.3.2.2 Stepper Motor Speed
        3. 8.3.2.3 Decay Modes
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.2 Current Regulation

The current through the motor windings is regulated by an adjustable, 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, inductance of the winding, and the magnitude of the back EMF present. When the current hits the current regulation threshold, the bridge enters a decay mode for a period of time determined by the TOFF pin setting to decrease the current. After the off-time expires, the bridge is re-enabled, starting another PWM cycle.

Table 7-4 Off-Time Settings
TOFFOFF-TIME tOFF
07 µs
116 µs
Hi-Z24 µs
330kΩ to GND32 µs

The TOFF pin configures the PWM OFF time for all decay modes except smart tune ripple control. The OFF time settings can be changed on the fly. After a OFF time setting change, the new OFF time is applied after a 10 µs de-glitch time.

The current regulation threshold is set by a comparator which monitors the voltage across the current sense MOSFETs in parallel with the low-side power MOSFETs. To generate the reference voltage for the comparator, the VREFx input is attenuated by a factor of Kv.

The chopping current (IFS) can be calculated as IFS (A) = VREFx (V) / KV (V/A) = VREFx (V) / 1.32 (V/A).