Motor control chip needs no sensor

The Toshiba TB6575FNG is a PWM sensorless controller for three-phase full wave brushless DC motors.

Available now from Marktech, the Toshiba TB6575FNG is a PWM sensorless controller for three-phase full wave brushless DC motors.

A brushless DC (BLDC) motor is a synchronous motor, which means the rotor position has to be known to generate the appropriate field.

BLDC motors are popular because of their durability, linear control characteristics, efficiency and torque-to-volume ratio.

Normally sensors (usually Hall-effect devices) are used to determine the rotor position.

These sensors are a disadvantage because they add to the system cost, are a source of failure, require extra wires, and are sensitive to EMI.

The TB6575FNG provides sensorless commutation and PWM current control for three-phase full-wave BLDC motors.

Rotation speed is controlled through a variable PWM duty cycle controlled by an analogue input voltage.

On receiving an analogue voltage command input, the rotor is aligned to a known position in DC excitation mode.

The rotation is started in forced commutation mode by applying a PWM signal to the motor.

As the rotor moves, back-EMF is measured and applied to the position signal input pin.

Subsequently the device switches from forced commutation to natural commutation (based on the back-EMF sensing) to drive the BLDC motor in sensorless mode.

Quantity pricing for the TB6575FNG is $1.40 in 5000-unit lots with free samples currently available.

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