What is a motor driver? Explaining its uses and features | Infineon Technologies Technical Column

A DC motor is a motor that runs on direct POWER SUPPLIES from a battery. A brushed DC motor has brushes made of small pieces of metal, which are connected to a commutator at both ends of the coil, allowing current to flow. The current generates a magnetic field in the rotor coil. This magnetic field repels or attracts the magnetic field generated by the stator, causing the rotor to rotate and move.
At this time, the speed of the DC motor can be precisely controlled by changing the amount of current sent to it, and the direction of rotation can be precisely controlled by changing the direction of the current. This control is performed by a brushed DC motor driver.

Brushless DC motors have no brushes and have a built-in permanent magnet, and by switching the coil through which current flows depending on the position of the magnetic pole, the permanent magnet rotates, causing the motor to move. However, brushless C motors do not have brushes to switch the direction of the current flowing through the coil, so a driver is required as a drive circuit to make this switch. It should also be noted that there are also commonly available DCBL motor drivers that do not "detect" the position of the magnetic field or "do not have a built-in sensor."

ROTATIONAL STEPPING MOTORS are powered by pulse signals. Unlike DC motors, the rotor rotates intermittently at a fixed angle. The rotation angle is predetermined, and the rotation speed is determined by the number of iron cores (pole) in the stator. When POWER SUPPLIES is turned on and off, current flows through the coil, generating magnetic force in the electromagnet in the stator. This generates a pulse signal that synchronizes with the rotor and causes the motor to rotate, moving the motor. Meanwhile, drivers generate pulse signals by regularly passing current according to the specified rotation speed. The more pulse signals there are, the faster the motor rotates, and the faster the pulse signal. In other words, drivers are used to precisely control the motor's speed and stopping position.

A motor driver IC is a dedicated circuit that brings together devices for stable and accurate control of motors such as DC motors and ROTATIONAL STEPPING MOTORS.
IC (short for Integrated Circuit) refers to an integrated circuit, which contains the circuits necessary for control as well as circuits with protection functions to ensure safe and stable operation, all in a single package. These motor driver ICs also vary depending on the type of motor. Therefore, it is necessary to use a driver IC that is appropriate for the motor you are using.
This is where the "absolute maximum ratings" standard becomes important.

If you try to control a motor without using a motor driver, you have to design each circuit required for control one by one, which makes the circuitry more complex. The number of components also increases, which increases the mounting area and means that the circuits cannot be integrated into the desired size. Not only that, it also affects the product size depending on the board size. These factors increase costs. Motor drivers solve these problems. Because the circuits required for control are already integrated into one, the circuit itself is more compact. In other words, motor drivers help make products smaller, lighter, and more cost-effective.

As the number of components increases, the circuit becomes correspondingly more complex, which naturally increases the design man-hours required for component placement and wiring design. As the circuit becomes more complex, evaluation of each circuit is also necessary. Each component has an absolute maximum rating, so the design must not exceed this, and simply put, the time required for evaluation increases. In the manufacturing process, the more complex the circuit, the longer it takes. However, because motor drivers are integrated circuits designed to drive motors, the effort required for wiring design can be reduced. Furthermore, simplifying the circuit shortens the time required for evaluation, which also reduces the man-hours required from design to manufacturing.

Many motor drivers have built-in protection functions to prevent overcurrent and overheating. If you don't use a motor driver, you will need to provide these protection functions yourself to ensure safety and stable operation. Designing and implementing individual circuits to detect current and temperature can make the circuitry complicated, making it difficult to develop products efficiently. However, if you use a motor driver, these protection functions are already implemented, so performance is also reliable.
In addition, the driver's performance is reliable, which contributes to improving product safety and reducing evaluation man-hours.