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Brushless DC vibration-motor driver

Low-voltage full-bridge has integrated Hall commutation and PWM speed control

Allegro's A1444 and A1445 are low-voltage, full-bridge brushless DC motor driver ICs with integrated Hall commutation and internal PWM (pulse-width-modulation) speed control. For applications that require rotor speed control and fast rotor start/stop cycles, the new devices integrate a Hall element, an H-bridge output driver and PWM speed control logic into a monolithic IC that includes reverse battery protection and output short-circuit protection. Commutation of the motor uses a single integrated Hall element sensor to detect the rotational position of an alternating-pole ring magnet. The chip operates down to 1.8 V; the voltage applied to the PDC (PWM duty cycle) pin externally controls the maximum speed of the motor by adjusting the internal PWM duty cycle of the output driver. A soft-switching algorithm reduces audible switching noise and EMI. Externally-controlled speed regulation and braking functions permit motor designs with faster acceleration and stopping times; a braking function enable pin also controls a micropower 'sleep' mode. The devices are optimised for vibration motor applications that require fast start-stop cycles, as in cellular phones, pagers, and hand-held video game controllers, and will also control low power fan motors rated at 5 V.