SLVA767A September   2016  – December 2016 SN75469 , TPL7407L , TPL9201 , ULN2003A , ULN2003B , ULN2003V12 , ULN2004A , ULQ2003A , ULQ2003A-Q1 , ULQ2004A , ULQ2004A-Q1


  1.   Stepper Motor Driving With Peripheral Drivers (Driver ICs)
    1.     Trademarks
    2. 1 Peripheral Driver (Driver IC) Overview
    3. 2 Stepper Motors
      1. 2.1 Unipolar Stepper Motors
      2. 2.2 Bipolar Stepper Motors
    4. 3 Stepper Motor Driving Overview
      1. 3.1 Unipolar Stepper Motor Driving Block Diagram
      2. 3.2 Detailed Design Considerations
      3. 3.3 Bipolar Stepper Motor Driving Block Diagram
      4. 3.4 Detailed Design Considerations
    5. 4 Stepper Motor Driving Patterns
      1. 4.1 Wave Drive Operation
      2. 4.2 Full-Step Operation
      3. 4.3 Half-Step Operation

Half-Step Operation

The half-step mode of operation is less commonly used compared to the full-step method, but is typically more common than the wave drive method, as it enables better stepper resolution with the same motor. One disadvantage to the half-step method is that the torque swings between that of the wave drive method and that of the full-step method. Some devices, however, have internal circuitry to limit current and reduce torque ripple when half-stepping. The half-step mode would likely be used in applications where increased resolution is required.

For this mode of operation, two phases of the motor are activated simultaneously followed by a single phase. This ultimately provides additional resolution relative to both the wave drive and full-step methods. Figure 14 and Figure 15 describe the step pattern required for the half-step method, while Figure 16 provides a pictorial representation of the motor steps. Depending on the motor, each step in the sequence will rotate a defined angular distance. Figure 16 represents a motor with 4 steps per revolution, but many common stepper motors will have 32 or 64 steps per revolution; furthermore, others can have even higher precision. Each step for the motor in Figure 16 spins the motor 45°. Note that the half-step method allows for twice the resolution of the full-step method because each step is half that of the full-step method.

HalfStep-LogicTable.gifFigure 14. Half-Step Logic Table
HalfStep-StepperCoilSequence.gifFigure 16. Half-Step Motor Coil Sequence
HalfStep-TimingDiagram.gifFigure 15. Half-Step Timing Diagram