Motor Drivers for Stepper, Brushed and Brushless DC (BLDC) Motor Applications

A motor driver is used to control the operation of an electric motor by managing the power delivered to it. It acts as an interface between a low-power controller, such as a microcontroller, and the motor, which requires higher current and voltage. A motor driver enables functions such as starting and stopping the motor, controlling speed, changing rotation direction and protecting the system from conditions like overheating or overcurrent. Motor drivers are commonly used in applications such as robotics, industrial automation, automotive systems and consumer electronics.

Gate drivers and motor drivers serve different roles in electronic control systems. A gate driver is designed to control the switching of power transistors such as MOSFETs or IGBTs, enabling efficient delivery of power in applications like inverters and motor control systems. A motor driver, by contrast, is a higher-level solution specifically intended to control a motor’s speed, direction and torque. Motor drivers often include gate-driver functionality along with additional circuitry such as power stages, protection features and control logic, making them a more complete solution for driving motors directly.

Yes. Motor drivers can be designed for both brushed DC motors and Brushless DC (BLDC) motors, but the control methods are different. A brushed motor driver typically controls voltage and current to manage motor speed and direction, often using an H-bridge configuration. A brushless motor driver is more complex because it must electronically commutate the motor phases using multiple transistors and control algorithms, sometimes with feedback from Hall sensors or sensorless detection methods. Many manufacturers offer dedicated drivers optimized specifically for either brushed or brushless motor applications.

A microcontroller (MCU) can generate control signals, but it usually cannot provide the voltage, current or protection needed to drive a motor directly. A standalone motor driver is designed specifically to handle the motor’s power requirements safely and efficiently. It can deliver higher current, control motor speed and direction, manage switching of MOSFETs, and provide built-in protections such as overcurrent, overtemperature, undervoltage and shoot-through prevention. Using a dedicated motor driver also simplifies the design process and reduces the load on the microcontroller, allowing the MCU to focus on higher-level control tasks such as communication, sensing and application logic.

Many motor drivers are intended to work together with a microcontroller rather than replace it. For example, the ATA6847 BLDC motor driver uses Pulse-Width Modulation (PWM) and Serial Peripheral Interface (SPI) signals from a microcontroller while handling the high-power gate driving, protection circuitry and current sensing needed for motor operation.

Yes. Many of our motor control solutions support both sensorless control and Hall-sensor-based control, depending on the motor driver, MCU or Digital Signal Controller (DSC) and firmware architecture.

• Examples are the ATA6847 and ATA6847L BLDC motor drivers that support:
  • Sensored or sensorless trapezoidal control
  • Sensorless Field-Oriented Control (FOC)
  • Hall-effect sensor inputs

Motor-driver ICs with integrated driver functions can work with a wide range of microcontrollers, depending on the control method:

• Many MCUs with PWM outputs can interface to some integrated three-phase BLDC motor drivers
  • Our three-phase brushless sensorless sinusoidal integrated drivers can be interfaced with a microcontroller by using simple PWM
• For more advanced motor control, these MCU and DSC families serve as suitable companions:
  • 8-bit PIC^® and AVR^® MCUs: Good for basic, cost-sensitive motor control applications
  • dsPIC33 DSCs: Well-suited for high-performance control such as variable speed, constant torque and FOC
  • 32-bit SAM and PIC32 motor-control MCUs
    • PIC32CM MC
    • SAM D2x/C2x
    • PIC32MK
  • These include motor-control peripherals including PWM, ADCs, comparators and position decoding

In automotive systems, many “smart actuators” are no longer just powered motors. They are electronically controlled subsystems that need to communicate with a central Electronic Control Unit (ECU). The integrated Local Interconnect Network (LIN) transceiver allows the motor-control module to directly connect to that communication network without needing a separate external LIN chip.

Typical use cases include:

• Seat adjustment motors
• HVAC blower motors
• Cooling fans
• Mirror positioning
• Trunk/liftgate actuators
• Small pumps

Why LIN is useful in these systems:

• Low-cost automotive networking
• Reduces Bill of Materials (BoM) and Printed Circuit Board (PCB) space
• Enables ECU communication
• Better diagnostics
• Power management and sleep behavior

To size a motor driver correctly, you generally work through three main constraints:

• Voltage
• Continuous current
• Peak/stall/transient current

Motor Driver Sizing Examples