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Allegro Micro rolls out sensorless BLDC motor controller

Posted: 18 Dec 2014 ?? ?Print Version ?Bookmark and Share

Keywords:BLDC? MOSFETs? PWM?

Allegro MicroSystems has released the A4963, a three-phase, sensorless brushless DC (BLDC) motor controller. The latest device is geared for use with external complementary P-channel and N-channel power MOSFETs, and has a DC supply voltage range of 4.2V to 50V.

The A4963 fits a range of applications since the output current requirements can be scaled up or down with external MOSFET selection. This motor controller is targeted at the consumer, industrial and white goods markets with end applications to include: pumps, blowers, power and garden tools, hair dryers, portable mixers, and airborne drones.

Sensorless BLDC

The A4963 controls a motor using block commutation (trapezoidal drive) where phase commutation is determined, without the need for HALL position sensors, by monitoring the motor back- EMF (bemf). The sensorless start-up scheme allows the device to operate over a range of motor and load combinations including high or low inertial or friction loads. The A4963 can operate from less than 100rpm to in excess of 30,000rpm, depending on the supply voltage and motor capability. Several operational modes are available including closed loop speed control, duty-cycle (voltage) control and current (torque limit) control. Operating mode and control parameters can be altered through an SPI compatible serial interface or through adjustable default settings preloaded into the on-chip EEPROM memory.

Motor operation is through a single line, low frequency, PWM duty cycle control input. An open drain output is provided to report motor commutation frequency (TACHO) or electrical cycle frequency. Startup (inrush) current and peak motor current are limited by an integrated fixed off time PWM current limiter. Integrated diagnostics provide indication of under voltage, over temperature, lost synchronisation and power bridge faults and can protect the power switches under most short circuit conditions. Faults are indicated by a single open drain output.

The A4963GLPTR-T is provided in a small, thermally enhanced 20-pin TSSOP with exposed thermal pad.

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