SLVSGF5A May   2023  – December 2023 DRV8845

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 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 Motor Configurations
      2. 7.3.2 Stepper Control Logic
      3. 7.3.3 DC Motor Control
      4. 7.3.4 PWM Current Control
      5. 7.3.5 Current Regulation and Decay Mode
      6. 7.3.6 Blanking Time
      7. 7.3.7 Charge Pump
      8. 7.3.8 Logic-Level Pin Diagram
      9. 7.3.9 Protection Circuits
        1. 7.3.9.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.9.2 VCP Undervoltage Lockout (CPUV)
        3. 7.3.9.3 Overcurrent Protection (OCP)
        4. 7.3.9.4 Thermal Shutdown (OTSD)
        5. 7.3.9.5 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. 7.4.4 Functional Modes Summary
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Application Schematics
    3. 8.3 Application Curves
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Bulk Capacitance
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.4 PWM Current Control

Each H-bridge is controlled by a PWM current control circuit that limits the load current to a desired value, ITRIP. Initially, a diagonal pair of source and sink MOSFET outputs are enabled and current flows through the motor winding and RSENSEx. When the voltage across the current sense resistor equals the voltage on the VREFx pin, the current sense comparator resets the PWM latch, which turns off the source driver.

The maximum value of current limiting is set by the selection of RSENSEx and the voltage at the VREFx input with a transconductance function approximated by:

ITRIPMax = VREF / (3 × RSENSE)

When H-bridge 3 and H-bridge 4 are paralleled, and SENSE3 and SENSE4 pins are shorted together, the maximum value of current limiting is set by:

ITRIPMax = 2 × VREF3 / (3 × RSENSE), where RSENSE is the sense resistor from the shorted SENSE pin.

Each current step is a percentage of the maximum current, ITRIPMax. The actual current at each step ITRIP is approximated by:

ITRIP = (% ITRIPMax / 100) x ITRIPMax

where % ITRIPMax is given in the Step Sequencing table.

It is critical to ensure that the maximum rating of ± 500 mV on each SENSEx pin is not exceeded.