Allegro Microsystem's New Brushless DC Motor Driver Integrates Hall Element Commutation Circuitry

Allegro introduces a new full-bridge motor driver designed to drive low voltage bipolar brushless DC motors. Commutation of the motor is achieved by use of a single Hall element sensor to detect the rotational position of an alternating-pole ring magnet. 

A high density CMOS semiconductor process allows the integration of all the necessary electronics.  This includes the Hall element sensor, the motor control circuitry, and the full output bridge. Low-voltage design techniques have been employed to achieve device functionality down to 1.8 V VDD.

This fully integrated single chip solution provides enhanced reliability (including reverse battery protection and output short circuit protection) and eliminates the need for any external support components. 

Allegro's A1442 employs a soft-switching algorithm to reduce audible switching noise and EMI interference. A micro power sleep mode can be enabled by an external signal, to reduce current consumption for battery management in portable electronic devices.

This feature allows for the removal of a FET transistor for switching the device on and off.  In addition, the device offers an active function for motor braking.

Motor braking can be used to improve stop/start cycles for caller ID feature in vibration mode.

The A1442 is optimized for vibration motor applications such as cellular phones, pagers, electronic toothbrushes, hand-held video game controllers, and low power fan motors. The small package outline and low profile make this device suited for use in applications where printed circuit board area and component headroom are at a premium.