SLVSAW3D July   2011  – January 2016 DRV8805

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Timing Requirements
    7. 6.7 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 Output Drivers
      2. 7.3.2 Indexer Operation
      3. 7.3.3 nENBL and RESET Operation
      4. 7.3.4 Protection Circuits
        1. 7.3.4.1 Overcurrent Protection (OCP)
        2. 7.3.4.2 Thermal Shutdown (TSD)
        3. 7.3.4.3 Undervoltage Lockout (UVLO)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Step Modes
  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 Motor Voltage
        2. 8.2.2.2 Drive Current
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
      1. 10.3.1 Power Dissipation
      2. 10.3.2 Heatsinking
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

The DRV8805 can be used to drive one unipolar stepper motor.

8.2 Typical Application

DRV8805 typ_app_slvsaw3.gif Figure 7. Typical Application Schematic

8.2.1 Design Requirements

Table 5 lists the design parameters for this design example.

Table 5. Design Parameters

DESIGN PARAMETER REFERENCE EXAMPLE VALUE
Supply Voltage VM 24 V
Motor Winding Resistance RL 7.4 Ω/phase
Motor Full Step Angle θstep 1.8°/step
Motor Rated Current IRATED 0.75 A
PWM frequency fPWM 31.25 kHz

8.2.2 Detailed Design Procedure

8.2.2.1 Motor Voltage

The motor voltage to use will depend on the ratings of the motor selected and the desired torque. A higher voltage shortens the current rise time in the coils of the stepper motor allowing the motor to produce a greater average torque. Using a higher voltage also allows the motor to operate at a faster speed than a lower voltage.

8.2.2.2 Drive Current

The current path is starts from the supply VM, moves through the inductive winding load, and low-side sinking NMOS power FET. Power dissipation losses in one sink NMOS power FET are shown in the following equation.

Equation 1. P = I2 × RDS(on)

The DRV8805 has been measured to be capable of 1.5-A Single Channel or 800-mA Four Channels with the DW package and 2-A Single Channel or 1-A Four Channels with the PWP package at 25°C on standard FR-4 PCBs. The maximum RMS current will vary based on PCB design and the ambient temperature.

8.2.3 Application Curves

DRV8805 wvfm01_current_ramp_vm_8p2v_slvsaw3.png
Figure 8. Current Ramp With a 16-Ω, 1-mH,
RL Load and VM = 8.2 V
DRV8805 wvfm03_ocp_with_8p2v_slvsaw3.png
Figure 10. OCP With 8.2 V and
OUT1 Shorted to VM
DRV8805 wvfm02_current_ramp_vm_30v_slvsaw3.png
Figure 9. Current Ramp With a 16-Ω,
1-mH RL Load and VM = 30 V
DRV8805 wvfm04_ocp_separated_tretry_slvsaw3.png
Figure 11. OCP Separated by tRETRY With VM = 8.2 V and OUT1 Shorted to VM