drivercircuits

Driving Stepper Motors from Microcontrollers

Review
- Stepper motor types
- Stepper motor sequence; wave, normal, half step
- Driving DC motors with discrete componenets
  - mosfet, inductive effects
  - pwm as a speed control
Basic Issues;
- Microcontroller may not provide enough electrical current or may operate at an electrical potential (Voltage) which is not compatible with the stepper motor.
- Circuits need protection from inductive load effects of the motor.
Options
- Create a circuit to drive (provide enough electrical current at the correct electrical potential (Voltage) with appropriate protection circuits to protect from inductiove effects) the stepper motor using discrete components. Disadvantages include cost and complexity.
- Use a dediacted Integrated Circuit specifically designed to drive these types of loads. Advantages; cost, simplicity
Examples of suitable chips
- Texas Instruments SN754410
  - we will use this one
  - inexpensive (less than $4.00)
  - internal thermal shutdown
  - internal clamping diodes
  - will drive 1 A but if you want more it is stackable
  - simple to use
- Microchip TC4424
  - up to 3A
- Allegro 3952
  - advanced features which can be used for motor braking or current control
Features of TI SN754410 (from TI Spec Sheet for SN754410)

SN754410 Stepper Motor Driver 2 Phase Motor (altered from TI Spec Sheet for SN754410)

SN754410 Stepper Motor Driver 4 Phase Motor (altered from TI Spec Sheet for SN754410)