3-Phase Brushless Motor Controller

December 22, 2014 | 23:53
3-Phase Brushless Motor Controller
3-Phase Brushless Motor Controller

The A4963 from Allegro Microsystems is a three-phase, sensor-less, brushless DC (BLDC) motor controller for use with external complementary P-channel and N-channel power MOSFETs.

It can be used as a stand-alone controller communicating directly with an electronic control unit (ECU) or in a close-coupled system with a local microcontroller (MCU). The motor is driven using block commutation (trapezoidal drive). It determines the phase commutation without any additional independent position sensors, but by monitoring the motor back-EMF (bemf). The sensor-less start-up scheme allows the A4963 to operate over a wide range of motor and load combinations.

Dedicated circuits allow the A4963 to operate over a wide range of motor speeds, from less than 100 rpm to in excess of 30,000 rpm, depending on the supply voltage and motor capability. Several operational modes are available including duty-cycle (voltage) control, current (torque limit) control and closed loop speed control. Operating mode and control parameters can be altered through an SPI compatible serial interface. Motor operation is controlled by a programmable PWM input that can be used to define the motor operating state and provide the proportional input for the selected operating mode.

Integrated diagnostics provide under-voltage, over-temperature and power bridge fault indication and can protect the power switches under most short-circuit conditions. Faults are indicated by a single open drain output which can also be used to pull the PWM input low.

The A4963 is packaged in a small, thermally enhanced 20-pin TSSOP with an exposed thermal pad.

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