SLVSD18C June   2015  – August 2017 DRV8880

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified System Diagram
      2.      Microstepping Current Waveform
  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
    6. 6.6 Indexer 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  Stepper Motor Driver Current Ratings
        1. 7.3.1.1 Peak Current Rating
        2. 7.3.1.2 RMS Current Rating
        3. 7.3.1.3 Full-Scale Current Rating
      2. 7.3.2  PWM Motor Drivers
      3. 7.3.3  Microstepping Indexer
      4. 7.3.4  Current Regulation
      5. 7.3.5  Decay Modes
        1. 7.3.5.1 Mode 1: Slow Decay for Increasing and Decreasing Current
        2. 7.3.5.2 Mode 2: Slow Decay for Increasing Current, Mixed Decay for Decreasing current
        3. 7.3.5.3 Mode 3: Mixed Decay for Increasing and Decreasing Current
        4. 7.3.5.4 Mode 4: Slow Decay for Increasing Current, Fast Decay for Decreasing current
        5. 7.3.5.5 Mode 5: Fast Decay for Increasing and Decreasing Current
      6. 7.3.6  Smart Tune
      7. 7.3.7  Adaptive Blanking Time
      8. 7.3.8  Charge Pump
      9. 7.3.9  LDO Voltage Regulator
      10. 7.3.10 Logic and Tri-Level Pin Diagrams
      11. 7.3.11 Power Supplies and Input Pins
      12. 7.3.12 Protection Circuits
      13. 7.3.13 VM UVLO (UVLO2)
      14. 7.3.14 Logic Undervoltage (UVLO1)
      15. 7.3.15 VCP Undervoltage Lockout (CPUV)
      16. 7.3.16 Thermal Shutdown (TSD)
      17. 7.3.17 Overcurrent Protection (OCP)
    4. 7.4 Device Functional 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 Stepper Motor Speed
        2. 8.2.2.2 Current Regulation
        3. 8.2.2.3 Decay Modes
        4. 8.2.2.4 Sense Resistor
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance Sizing
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RHR|28
  • PWP|28
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.4 Current Regulation

The current through the motor windings is regulated by an adjustable fixed-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. After the current hits the current chopping threshold, the bridge enters a decay mode for a fixed period of time to decrease the current, which is configurable between 10 and 30 µs through the tri-level input TOFF. After the off time expires, the bridge is re-enabled, starting another PWM cycle.

Table 5. Off-Time Settings

TOFF OFF-TIME tOFF
0 20 µs
1 30 µs
Z 10 µs

The PWM chopping current is set by a comparator which compares the voltage across a current sense resistor connected to the xISEN pin with a reference voltage. To generate the reference voltage for the current chopping comparator, the output of a sine lookup table is applied to a sine-weighted DAC, whose full-scale output voltage is set by VREF. This voltage is attenuated by a factor of Av. In addition, the TRQx pins further scale the reference.

DRV8880 current_reg_lvsd18.gifFigure 14. Current Regulation Block Diagram

The full-scale (100%) chopping current is calculated as follows:

Equation 1. DRV8880 eq_I_FS_lvsd18.gif

The TRQx pins are the inputs to a Torque DAC used to scale the output current. The current scalar value for different inputs is shown below.

Table 6. Torque DAC Settings

TRQ1 TRQ0 CURRENT SCALAR (TRQ) EFFECTIVE ATTENUATION
1 1 25% 26.4 V/V
1 0 50% 13.2 V/V
0 1 75% 8.8 V/V
0 0 100% 6.6 V/V

Table 7 gives the xISEN trip voltage at a given DAC code and TRQ[1:0] setting for 1/16 step mode. In this table, VREF = 3.3 V.

Table 7. xISEN Trip Voltages over Torque DAC and Microsteps

1/16 STEP (SINE DAC CODE) TORQUE DAC TRQ[1:0] SETTING
00 – 100% 01 – 75% 10 – 50% 11 – 25%
16 500.0 mV 375.0 mV 250.0 mV 125.0 mV
15 490.0 mV 367.5 mV 245.0 mV 122.5 mV
14 480.0 mV 360.0 mV 240.0 mV 120.0 mV
13 460.0 mV 345.0 mV 230.0 mV 115.0 mV
12 440.0 mV 330.0 mV 220.0 mV 110.0 mV
11 415.0 mV 311.3 mV 207.5 mV 103.8 mV
10 385.0 mV 288.8 mV 192.5 mV 96.3 mV
9 355.0 mV 266.3 mV 177.5 mV 88.8 mV
8 315.0 mV 236.3 mV 157.5 mV 78.8 mV
7 280.0 mV 210.0 mV 140.0 mV 70.0 mV
6 235.0 mV 176.3 mV 117.5 mV 58.8 mV
5 190.0 mV 142.5 mV 95.0 mV 47.5 mV
4 145.0 mV 108.8 mV 72.5 mV 36.3 mV
3 100.0 mV 75.0 mV 50.0 mV 25.0 mV
2 50.0 mV 37.5 mV 25.0 mV 12.5 mV
1 0.0 mV 0.0 mV 0.0 mV 0.0 mV