Motor drivers are electronic components that bridge the gap between digital control signals and real-world power delivery. They amplify low-power input signals to drive the motor coils and have built-in sensors, voltage regulation, PWM generation, and braking capabilities.
They can even be controlled without a microcontroller. All you need is a potentiometer and a 3-position switch to manually adjust motor speed and direction.
Power Supply
The power supply of a motor driver is critical to its operation. Unlike many microcontrollers, motors require high current and different voltage levels to run. The motor driver acts as an intermediary between the host controller and the motor, providing power in response to the controller’s commands to control motor speed and torque.
The motor driver ICs come in a wide variety of types and offer different features and characteristics. Some drivers have advanced switch technologies like gallium nitride that improve efficiency, while others incorporate built-in sensors to monitor position and speed. Still other features include adaptive performance to automatically adapt to changing load dynamics and regenerative braking to recapture energy from the motor during braking phases.
One of the most common uses for a motor driver circuit is to convert digital logic PWM input signals to analog voltages that can drive the motor windings. The power stage in a driver does this by switching transistors on and off in patterns that determine current flow and rotation direction.
Whether you’re using a motor driver or another type of motion control component, proper layout is key to getting the most from your design. Avoid shorting out pins and make sure the power motor driver leads are routed away from your logic connections to minimize noise. Decoupling capacitors are a good idea across the power and ground connections to further reduce noise and electromagnetic interference.
Motor Control
Motor drivers take low-power control signals from a microcontroller and amplify them to deliver the required power to the motor coils. They also feature additional components for voltage regulation, PWM generation, braking, current sensing and protection to ensure optimal operation. This makes them a critical component of robotics projects because they serve as a seamless bridge between digital controls and real-world power delivery.
To determine which type of motor driver is best for your project, evaluate the torque needs of your application. The stall torque (required to prevent the motor from moving) and holding torque (needed to overcome load resistance) are important factors in choosing the right motor driver for your system.
If you’re using sinusoidal commutation, select a motor driver with a built-in pulse generator. This enables you to directly connect the motor driver to a host programmable controller, saving space and simplifying wiring.
H-bridge motor drivers provide the easiest way to control direction and speed for brushed DC motors. By activating one of the two switch pairs, you can change which polarity the motor applies to the coils. Closing switches 1 and 2 makes the current flow from one side of the coil to the other, causing the motor to spin clockwise or counterclockwise. Closing switches 3 and 4 reverses the polarity of the current, spinning the motor in the opposite direction.
Reliability
Reliability is a term that many associate with quality, as in a car that runs well and stays safe for years to come. It also refers to how well a product works and lasts, such as a computer or a home appliance. A motor driver is a component in a motor control system that connects the microcontroller to the motor. It receives input controls and enhances them to achieve smooth, accurate speed regulation and torque delivery.
The reliability of a motor driver depends on several factors, including its internal MOSFETS, circuitry layout, and firmware (software). In addition to this, heat dissipation can impact current ratings. This is because the power that’s dissipated can cause the device to overheat, which would affect its performance and lifecycle.
Motor drivers have built-in overcurrent protection (OCP) circuits that limit the drive current to a level that’s safe for the silicon, protecting it from damage. TI’s motor driver ICs all have this feature.
Proper PCB construction is also important to maintaining the reliability of a motor driver. This includes proper thermal pad pours and connections, copper thickness, and the use of thermal vias. This helps with effective heat dissipation and ensuring that the device is operating within its safe temperature range. It also means minimizing internal quiescent power and switching losses. The thermal estimations can help maintain the motor driver IC’s designed current capabilities over time.
Design
The motor driver takes a low-power digital signal from the microcontroller, amplifies it and converts it to a high-current power output for driving the motor. It also contains built-in sensors for stall detection and power-off braking to protect the motor from damage and provide functional safety.
Choosing a motor driver requires careful consideration of the application’s torque needs, particularly stall and holding torque. The driver’s PWM frequency is another critical design element. Lower frequencies reduce current loss and increase efficiency, but very high frequencies may overdrive the gate drive and transistor switches and cause them to fail.
In addition, you should consider the interface type. The most common is H-bridge, motor driver wholesale which controls the motor direction and speed, but alternatives like L293D, L298N, and TB6612FNG offer different functionalities. The logic level is important, too. Most microcontrollers use TTL logic, which isn’t compatible with many motor drivers, so you should select a logic-level converter.
Finally, the design of a motor driver should take into account its size and cost. For example, using a monolithic integrated circuit (IC) with internal power devices is less expensive and smaller than a solution that uses gate drive ICs plus external power MOSFETs. Choosing a driver with slew rate control and internal diagnostic functions can further reduce its footprint, which will minimize PCB space used in the motor controller system.