Highly Integrated IC Drives Vibration Motors

The A1442 full-bridge motor driver from Allegro MicroSystems Inc. targets low-voltage, bipolar, brushless dc motor applications. Commutation is achieved by a single Hall sensor that detects the rotational position of an alternating-pole ring magnet. A high-density CMOS process allows the integration of all the necessary electronics, including the Hall element, the motor-control circuitry, and the full output bridge. The chip includes reverse-battery protection and output short-circuit protection, eliminating the need for any external support components. Also, low-voltage design techniques allow the IC to function down to 1.8 V DD.

The driver is optimized for vibration-motor applications, such as cell phones, pagers, electronic toothbrushes, handheld games, and low-power fans. A soft-switching algorithm reduces audible switching noise and electromagnetic interference. For battery management in portable systems, users can activate a micropower sleep mode that reduces current consumption and eliminates the need for a FET to switch the device on and off. In addition, the driver’s active motor-braking function can be used to improve start/stop cycles for caller ID features in vibration mode. The A1442 is available in a lead-free, six-pin micro-leadframe package (MLP) for surface mounting, with an exposed pad for enhanced heat dissipation.