What is Motor Driver? Everything You Need to Know


Prof. David Reynolds stands as a luminary in the field of electrical engineering, renowned for his expertise in integrated circuits. Holding a distinguished position as a Professor of Electrical Engineering, Prof. Reynolds earned his acclaim through decades of research, teaching, and industry collaboration.

Are you interested in understanding how motors are managed in devices such as robots, drones, and CNC machines?  Motor drivers are crucial components in any robotics or automation project, serving as the powerhouse that drives motors and other elements within the setup. These drivers are tasked with delivering the necessary voltage, current, directionality, and protection to ensure the efficient operation of your robotic devices. By seamlessly integrating with a microcontroller board, motor drivers facilitate easy customization of settings like acceleration/deceleration rates, encoder readings, and PID tuning parameters, thereby enhancing system performance without being hindered by hardware constraints. This capability is vital during troubleshooting phases, particularly in deployment, as motor drivers significantly influence operational precision in industrial production where accurate motion systems and continuous data monitoring are paramount.


In the realm of electronic devices and machines, motors are among the most prevalent actuators, standing alongside solenoids, pneumatics, and hydraulics. These DC machines range from simple vibration motors in smartphones to complex stepper motors in CNC machinery. To manage these motors, a Motor Driver or Motor Controller is essential. These devices vary in design based on the motor type and required control level. This discussion focuses on DC motors and the control of these motors using Motor Drivers, specifically employing the widely-used H-bridge topology. This method is key for operating both small and large DC motors and for managing their directional control. This article overviews the motor drivers, including the various types and their functionality, how the motor driver works, the characteristics, types, etc. Additionally, you'll discover insights into the H-bridge circuit, constructing a motor driver circuit, and controlling the direction of a DC motor using transistors. To help you know how to choose the right one.



What is a Motor Driver?

A motor driver IC is a type of integrated circuit that orchestrates motor control in autonomous robots and embedded systems. Common examples like the L293D and ULN2003 are frequently employed in basic robotic applications and remote-controlled cars. Essentially, a motor driver acts as a mediator, translating low-voltage commands from a controller or processor into the high voltage necessary to drive a motor. It regulates the motor's direction based on input signals, effectively communicating instructions to the motor.

In broader terms, a motor is an electronic component that transforms electrical energy into mechanical motion, facilitating automated tasks through electrical power. There are various kinds of electric motors, such as DC motors, stepper motors, and servo motors, each defined by specific operational principles and characteristics. Selecting the appropriate motor driver is crucial as it ensures that the motor operates seamlessly with your chosen microcontroller, optimizing both functionality and efficiency.


Types of Motor Drivers

DC Motor Drivers

A DC drive's primary function is to convert alternating current (AC) into direct current (DC) to power a DC motor. These drives are power modules that act as the interface between a DC motor and a controller. Often, the motor comes with an integrated controller and drive circuit, which helps to power the control signals that communicate with the drive.

There are several types of DC motor drives, with the most common type using two SCRs (Silicon Controlled Rectifiers) that utilize a single-phase AC input to produce a half-cycle DC output. This method is known as a half-bridge method. More complex and powerful DC drives use six SCRs to implement a full-bridge method, relying on a three-phase AC input to generate the DC output.

DC drives are sometimes called variable speed drives due to their ability to adjust the shaft speed. A DC drive is typically known for its reliable speed regulation, wide speed range, and efficient voltage transfer to the motor.

Various DC motors depend on DC drives, all operating with the same basic principle: motor rotation is achieved by applying power through current-carrying conductors within a magnetic field. Differences between DC motors arise in the creation and location of the electromagnetic fields. There are two main types of DC motor drives: brushed and brushless.


DC Motor Driver Circuit


Brushed DC Motor Drivers

A brushed motor is a type of DC motor that uses physical contact for commutation to produce mechanical energy. The brushes, typically made of carbon or other materials, serve as electrical contacts. As the shaft rotates, spring-loaded brushes make contact with the commutator. Essentially, the motor's brushes facilitate the connection between the DC power supply and the rotor assembly, which includes the output shaft, commutator rings, and armature.

These brushed motors have been trusted for over a century due to their high torque-to-inertia ratio. They are known for their reliability and affordability. Common applications include power windows, windshield wipers, and seat adjusters in vehicles. They are also found in battery-powered pumps, X-ray machines, and welding equipment. In industrial settings, brushed motors are used in equipment requiring quick bursts of power.




Brushless DC Motor Drivers

In contrast to brushed motors, brushless motors do not rely on physical contact for commutation. They do not use brushes to generate motion. Instead, they use magnets placed around the rotor, which are attracted to the stator's powered coil windings. This design generates torque through electromagnetism. The motor's rotation speed can be adjusted by changing the direction and magnitude of the current in the stator coils.

Due to their efficiency and durability, brushless DC motors are ideal for applications requiring prolonged operation. Examples include hard drive disks, washing machines, computer fans, and air conditioners.



Common DC motor driver IC: A4988, L293, DRV8833


Servo Motor Drivers

A servo motor is one of the most efficient motors that users can easily control to achieve precise output. This motor type utilizes a servo drive to generate accurate movements for rotating or pushing machine parts. A servo drive adjusts the input power by converting an alternating or constant current source into a pulsed current output with varying pulse frequency and duration. These drives help manage positions, torques, and motor speeds.

Servo motors come in two main sizes: small and standard. As expected, the standard-sized motor provides greater speed and power compared to smaller systems. Small servo motors are ideal for applications with limited space and lower power requirements. Standard servo motors, often built with metal components, handle heavier workloads, while small servos typically use plastic parts for lighter tasks.



Common Servo motor driver IC: L293


Stepper Motor Drivers

A stepper motor drive and controller convert alternating or constant current sources into a stepped current output, which then adjusts the stepper motor's input power. These devices are also known as step amplifiers and pulse drives due to their function. Stepper motor drives regulate input power using permanent magnets and precisely positioned poles in both the stator and rotor, which utilize DC currents to achieve stepwise rotation.

Because a stepper motor's rotational output is not continuous, the input power must be managed to ensure that groups of stator poles are either energized or de-energized correctly. The drives and controllers are essential for providing the necessary control for the stepper motor to operate efficiently. Specifically, the controller integrated with the stepper drive circuit sends the appropriate control signals to the motor drive.



Common Stepper motor driver IC: A4988, L293, DRV8833, ULN2003


Key Components of Motor Drivers


Block Diagram of Motor Driver



The controller, which can be a microprocessor or a microcontroller, manages the motor's operations.


Motor Driver IC or Motor Driver Circuits

These are current amplifiers that take a low current signal from the controller and convert it into a high current signal to drive the motor.



A motor is an electric or mechanical device that creates motion. When interfacing with the controller, motors such as DC motors, stepper motors, and brushless DC motors may require a driver IC or driver circuit. A DC motor converts DC into mechanical power. A brushless DC motor includes a DC power source and an inverter that produces an AC signal to drive the motor. A stepper motor, which is a brushless DC electric motor, converts electrical pulses into discrete mechanical movements.


Power Supply Unit

This unit provides the necessary power to the motor driver.


Motor Drivers Characteristics

Compatible Motors

Finding a motor driver that suits all types of electric motors is impractical. Manufacturers often design motor drivers specifically for certain motor types, providing a list of compatible motors for each driver model.

Most drivers are generally compatible with DC and stepper motors. However, selecting a motor driver for a servo motor requires more careful consideration.



Many motor drivers seamlessly integrate with Arduino driver board interfaces. However, certain applications, especially wireless projects, may necessitate a wireless motor driver. For instance, a Bluetooth controller board is ideal for wireless project control.


Voltage and Current

Voltage and current ratings are crucial characteristics when selecting a motor driver. It's essential to know the required supply voltage and operating current for your project. Ensure the chosen driver meets these specifications to ensure optimal functionality.


How Does a Motor Driver Work



Initially, the microcontroller sends signals to the motor driver. The motor driver interprets these signals and amplifies them using a reference voltage supplied for motor operation. The motor typically has two input pins for voltage: Pin 1 activates the motor by applying a voltage equal to the reference voltage, while Pin 2 deactivates the motor by outputting 0V. This entire process is managed by the motor driver, which boosts the microcontroller's low-voltage signal to provide sufficient power to the motor.

When the microcontroller sends a HIGH input to the motor driver, the driver rotates the motor in one direction, keeping one pin HIGH and the other LOW. Conversely, a LOW input from the microcontroller causes the motor driver to rotate the motor in the opposite direction by alternating between LOW and HIGH states on the motor pins.

Motor drivers play a critical role in machines and robotic systems, enabling motor operation from higher-level signals such as pulse-width modulation (PWM) or analog signals similar to those used with servos. Motor driver circuits typically incorporate integrated circuits capable of supplying sufficient current to drive the motor, along with mechanisms for precise speed control through power transistors arranged in parallel.

By configuring these transistors correctly, motor coil voltage spikes during rapid switching can be effectively managed without compromising efficiency during normal operations. Moreover, many modern motor driver designs include features such as built-in sensors for detecting stall conditions, as well as protections against over/under voltage and active braking capabilities. These attributes make motor drivers ideal solutions for a wide range of applications, from simple automation tasks to complex robotics projects.




How to Stop the Motor (Braking)

When stopping a motor, you have two primary options:

  • Coasting: This involves removing power from the motor. The drawback is that the motor will continue spinning for a period, which could cause damage to itself or its connected components.
  • Braking: In braking, power is applied to the motor in the opposite direction, causing it to stop almost immediately. However, this method can impose significant stress on the motor and potentially lead to damage.

The choice between coasting and braking depends on your specific application. If rapid stopping is necessary, braking is the preferred method. If allowing the motor to spin down naturally after power removal is acceptable, coasting can be used.

An analogy can help illustrate the choice: Imagine riding a bike downhill where coasting would be preferable, whereas going uphill would require braking.

Consider also the type of motor being used. For brushed DC motors, selecting a motor driver capable of handling their high current requirements is essential. Similarly, for stepper motors, a motor driver capable of micro-stepping is necessary.


What is an H-bridge Circuit?

An H-bridge is a basic circuit that enables control of a DC motor to move in either direction.

Typically, it is used in conjunction with a microcontroller like Arduino for motor control.

With the ability to independently control two motors for forward and backward movement, you can construct your robot!

Here's how the H-bridge concept works using switches:



A DC motor changes direction based on how you connect its positive and negative terminals.

By closing switches 1 and 4, the positive terminal connects to one side of the motor and the negative terminal to the other, causing the motor to spin in one direction.



Alternatively, closing switches 2 and 3 connects the positive terminal to the opposite side and the negative terminal to the original side, making the motor spin in the opposite direction.



How to Build a Motor Driver Circuit

Motor driver circuits can be constructed using readily available integrated ICs. Alternatively, you can utilize transistor circuits to manage the direction and speed of a DC motor. To control the motor's speed, a PWM signal from a microcontroller such as Arduino can be applied to the transistor's base. Below, we'll explore how to control the direction and speed of a DC motor using motor driver circuits built with transistors.


Direction Controlling circuit of a DC motor using Transistors



The circuit diagram above is designed to regulate both the speed and direction of a DC motor. In this setup, four transistors are employed for controlling these motor parameters. The PWM signal from microcontrollers like Arduino, Raspberry Pi, or ESP32 serves as the base drive for these transistors.

A crucial consideration when operating motors is their ability to generate electrical energy. When halting the motor by turning off the transistors, this energy must be dissipated safely. Diodes placed in reverse across the transistors provide a path for the current, preventing voltage spikes that could otherwise damage the transistors.

Additionally, resistors connected to each transistor base limit the current flow. If using a microcontroller for control, starting with 1kΩ resistors is generally a good practice, adjusting as necessary based on performance.

This entire circuit necessitates a voltage source and a PWM signal for each transistor to manage the motor's speed and direction effectively. Always ensure that two transistors operating in opposite directions receive appropriate PWM signals for precise motor control.


Applications of Motor Drivers

Robotics and Automation Systems

Motor drivers play a crucial role in robotics and automation systems by enabling precise control over actuators and movement. They facilitate the operation of DC motors, stepper motors, and servos, supporting tasks such as navigation, object manipulation, and automated processes. Integrated into circuit boards, these drivers manage motor speed, direction, and torque to ensure accurate and efficient system performance.


Computer Numerical Control (CNC) Machines

In CNC machines, motor drivers govern stepper or servo motors to achieve precise movements across multiple axes. These drivers receive step and direction signals from control software, translating them into mechanical actions. Embedded within CNC machine circuitry, motor drivers, and associated electronics guarantee precise machining, cutting, and milling operations.


3D Printers and Additive Manufacturing Equipment

Motor drivers in 3D printers control stepper motors responsible for moving the print head and building the platform. By regulating motor movements with precision, they ensure accurate layering and high-quality prints. Integrated within printer circuit boards, motor drivers, along with microcontrollers and sensors, coordinate the printing process and material extrusion.


Automotive Systems (Power Windows, Sunroofs, etc.)

Motor drivers are essential components in automotive systems for controlling electric motors used in power windows, sunroofs, and seat adjustments. These drivers manage motor speed and torque, ensuring smooth and reliable operation of vehicle mechanisms. Integrated into automotive circuit boards, motor drivers, along with control switches and sensors, provide responsive interfaces for vehicle occupants.


Industrial Machinery and Equipment

Motor drivers are integral to industrial machinery, regulating motors in conveyors, pumps, and robotic arms. They deliver precise control over motor functions, enhancing automation and efficiency in manufacturing operations. Embedded within industrial equipment circuitry, motor drivers, power management systems, and feedback mechanisms ensure robust and dependable motor performance in challenging industrial environments.


How to Choose the Right Motor Driver

When choosing a motor driver, several factors are crucial to consider:


1. Motor Type (Brushed or Brushless):

Begin by identifying whether you are using brushed or brushless motors. Refer to the motor datasheet if you need clarification.


2. Voltage Requirements:

Select a motor driver that matches the voltage rating of your motor, accommodates the logic level of your microcontroller, and offers the necessary features and capabilities. Most motor drivers can handle a range of voltages, such as the L293D, which supports +36V to -36V. Always ensure your operating voltage stays within the driver's specified limits to prevent damage.


3. Current Capacity:

Ensure the motor driver can handle the current drawn by your motors. Using an insufficiently rated driver can overheat and damage your motors, while an excessively powerful one may be unnecessarily costly. For instance, the L293D can supply up to 600mA per channel, suitable for larger motors requiring higher currents.


4. Control Interface:

Consider the interface type, with H-bridge being the most common for controlling motor direction and speed. Alternatives like L293D, L298N, and TB6612FNG offer different functionalities. If your microcontroller uses TTL logic, which isn't always compatible with motor drivers, use a logic-level converter.


5. Torque Requirements:

Evaluate the torque needs, particularly stall torque (required to prevent motor movement) and holding torque (needed to overcome load resistance). Applications involving heavy loads necessitate motors with a higher holding torque.


6. Speed Requirements:

Choose motor drivers capable of providing sufficient power to achieve the required motor speed for your application.


7. Motor Size and Weight:

Ensure the motor drivers can support the size and weight of your motors without performance compromise.


8. Environmental Considerations:

Select motor drivers suited for your application's environment, whether indoor or outdoor. Outdoor applications require weatherproof motor drivers for durability and reliability.


9. Budget Constraints:

Factor in cost when selecting motor drivers. Choose options that align with your budget while meeting all technical requirements.


When making your decision, prioritize compatibility with your motor type, voltage and current ratings, control interface suitability, torque and speed requirements, environmental suitability, and budget considerations. This approach ensures you select the optimal motor driver for your specific application.


What are the Functions of Motor Driver ICs?

The functions of motor driver ICs include:

  • Supplying power to the motor
  • Controlling the speed and direction of the motor
  • Enabling braking of the motor
  • Protecting the motor from damage due to excessive current
  • Providing a current-limiting feature


Advantages & Disadvantages of Motor Driver ICs


  • Enhanced Power Output: These ICs are capable of delivering more power compared to a microcontroller.
  • Integrated Protection: They come equipped with protections against over-current and over-temperature scenarios.
  • Space Efficiency: By integrating both the amplifier and the motor driver functionalities into a single IC, these devices help conserve space.



  • Cost: Motor driver ICs can be relatively costly.
  • Voltage and Current Considerations: It's crucial to monitor the voltage and current specifications to ensure compatibility closely.
  • Usability Challenges: Certain motor driver ICs may present complexities in usage, making them less user-friendly for some applications.


Most Common Motor Driver ICs

L298N Dual H-Bridge Motor Driver

The L298N is a robust and widely used dual H-Bridge motor driver that can control the speed and direction of two DC motors simultaneously. It can handle a wide range of voltage inputs, typically from 5V to 35V, and can provide a continuous current of up to 2A per channel. Key features include:

  • High current capability
  • Thermal shutdown and overcurrent protection
  • Logic voltage compatibility with microcontrollers
  • Easy interfacing with Arduino and other development boards



DRV8833 Dual H-Bridge Motor Driver

The DRV8833 is a dual H-Bridge motor driver IC known for its compact size and efficient performance. It supports a voltage range of 2.7V to 10.8V and can deliver a continuous current of up to 1.5A per channel. Key features include:

  • Low RDS(on) for better efficiency
  • Built-in protection against overcurrent, overtemperature, and Undervoltage lockout
  • PWM control for precise motor speed regulation
  • Small footprint, making it ideal for space-constrained applications



TB6612FNG Dual Motor Driver

The TB6612FNG is a versatile dual-motor driver that can control two DC motors or one stepper motor. It operates within a voltage range of 4.5V to 13.5V and can supply a continuous current of 1.2A per channel, with a peak current of 3.2A. Key features include:

  • High efficiency with low standby current
  • PWM control for smooth speed adjustment
  • Integrated protection features, including thermal shutdown and overcurrent detection
  • Easy to use with popular microcontrollers like Arduino and Raspberry Pi



These motor driver ICs are commonly used in a variety of applications, from simple robotics projects to more complex industrial automation systems, due to their reliability, ease of use, and comprehensive feature sets.


Other Motor Driver ICs/Boards

  • L293D IC
  • BTS7960B motor driver board
  • TB6560 motor driver board
  • PCA9685 16-channel Servo motor driver board
  • MACH3 Interface Board CNC 5 Axis
  • TB6600 stepper motor driver
  • PWM DC motor speed controller
  • 2000W 220V AC motor speed control board
  • L298 Motor driver board
  • A4988 stepper motor driver
  • DRV8825


Troubleshooting Motor Drivers


  • Adequate Cooling: Use heat sinks or fans to dissipate excess heat.
  • Check Load and Duty Cycle: Ensure the motor and driver are not operating beyond their rated capacity.


Noise Issues

  • Proper Grounding: Implement good grounding practices to minimize electrical noise.
  • Shielding and Routing: Use shielded cables and careful routing to prevent electromagnetic interference.


Latest Developments in Motor Driver Technology

Smart Drivers

  • Integrated Sensors: New drivers include built-in sensors for detecting position, speed, and load, allowing for more sophisticated control.
  • Adaptive Performance: Advanced algorithms enable drivers to adapt to changing load dynamics in real-time.


Energy Efficiency Improvements

  • Advanced Switching Techniques: Techniques like gallium nitride (GaN) transistors offer higher efficiency and faster switching speeds.
  • Regenerative Braking: Some drivers can now recapture energy during braking phases and feed it back into the power system.


The Future of Motor Drivers

  • Increased Integration: Future drivers will integrate more control features and power components into single packages.
  • AI and Machine Learning: Use of AI to predict failures and optimize performance.
  • Sustainability: Focus on reducing power consumption and enhancing the lifecycle of products.


Motor Drivers vs. Motor Controllers


Feature Motor Driver Motor Controller
Function Operates as the interface between a microcontroller and the motor. Manages all aspects of motor operation, including the driver part.
Control Signals Receives simple directional and speed commands. Receives complex commands, potentially including positioning, torque control, and feedback algorithms.
Complexity Typically simpler, handling basic power amplification. More complex with integrated circuits for full control functionalities.
Components Includes power amplifiers, basic H-bridge circuits. Includes drivers, microprocessors, feedback loops, sometimes sensors for precise control.
User Interaction Minimal; direct implementation of commands. High; involves setting parameters, configurations, and adjustments.
Feedback Limited to basic current/voltage sensing if at all. Advanced feedback like position, speed, load, and error diagnostics.
Applications Suitable for simple applications like toys, basic automation. Used in sophisticated systems like robotics, industrial automation where precise control is needed.
Cost Generally less expensive. More expensive due to added functionalities and components.
Programming Requires minimal programming. Requires detailed programming and configuration.
Integration Easy to integrate with limited external components. Might require additional modules like sensors and communication interfaces.



Motor driver ICs are essential components for controlling stepper or DC motors. These drivers come in a variety of types, each offering specific benefits and limitations. When selecting a motor driver, it's crucial to evaluate the voltage and current specifications of your motor and ensure the driver can accommodate the maximum power dissipation allowed for the chip. Additionally, the driver must be capable of managing the switching frequency needed by your motor.

Due to their inability to drive high-power motors directly, most standard microcontrollers (MCUs) require an external motor driver when operating high-power DC or stepper motors. Motor drivers not only facilitate this but also help maintain appropriate logic levels within the circuit. With ongoing technological advancements, the use of motors in various applications has become increasingly prevalent.


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  • What does the motor driver do?

    Motor drivers perform several critical roles in motor control systems. Primarily, they amplify electrical signals to provide the necessary power to operate the motor. Additionally, they enable precise control over the motor's speed and incorporate strong safety features, including over-current protection (OCP) and over-temperature protection (OTP). These protections help prevent damage to the motor and the driver from excessive current or heat.

  • What is the role of the motor drive?

    The motor drive's primary function is to take electrical energy from its source and deliver it to the motor. It enables precise control over factors such as motor speed, torque, and shaft position to achieve the desired mechanical output.

  • Why do I need a motor driver?

    A motor driver is essential because microcontrollers operate at lower voltage levels than motors. As a result, direct power supply from the microcontroller to the motor is not feasible. Therefore, a motor driver is required to interface between these electrical components.

  • What is the most common motor driver?

    One of the most common types of DC motor drivers utilizes two SCRs (Silicon Controlled Rectifiers) and operates on single-phase AC input to produce a half-cycle DC output. This method of power conversion is commonly known as the half-bridge configuration.

  • What is a motor driver called?

    A motor driver is also referred to as a motor controller.

  • Can motor drivers be used with any motor?

    Yes, motor drivers can be used with various types of motors, including DC motors, stepper motors, and certain types of AC motors. Compatibility with the specific motor type is important for optimal performance.

  • What is the function of the motor module?

    Motor modules are linked together via a common DC busbar. This shared DC link enables energy exchange between modules. For instance, if one module is generating energy as a generator, another module can utilize this energy while operating as a motor.

  • What is a motor control circuit?

    Motor control circuits can range from basic two-wire on/off setups that activate a motor starter to more complex three-wire configurations. These advanced circuits include multiple pushbutton stations and motors that start sequentially.

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