Sensorless Sinusoidal Drive BLDC Controller

The A4964 is a three-phase, sensorless, brushless DC (BLDC) motor controller for use with external N-channel power MOSFETs and is specifically designed for automotive applications. It is designed to provide the motor control functions in a system where a small microcontroller provides the communication interface to a central ECU and intelligent fault and status handling. The A4964 provides the supply and watchdog for the microcontroller and the high-voltage interfaces between the microcontroller and the central ECU and ignition switch. The A4964 can also operate as an independent singlechip remote motor controller.

The motor is driven using 3-phase sinusoidal current drive where phase commutation is determined, without the need for independent position sensors, by monitoring the motor back-EMF (bemf). The sensorless start-up scheme includes forward and reverse pre-rotation (windmill) detection and synchronization, and allows the A4964 to operate over a wide range of motor and load combinations.

The A4964 can operate with duty cycle (voltage) control, current (torque limit) control, and closed-loop speed control. Control mode, operating mode, and control parameters are programmed through an SPI-compatible serial interface.

A single current sense amplifier provides peak current limiting and average current measurement through the serial interface.

Integrated diagnostics provide indication of undervoltage, overtemperature, and power bridge faults and can protect the power switches under most short-circuit conditions.

The A4964 is provided in a 36-terminal QFN and a 32-lead QFP, both with exposed thermal pad.