Allegro MicroSystems, Inc. Introduces New Dual Full-Bridge Motor Driver ICs With Overcurrent Protection

Improved Microstepping Accuracy for High Reliability Designs

June 29, 2010

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Worcester, MA – Allegro MicroSystems, Inc. introduces two new motor driver ICs to complement their existing motor driver family. Allegro’s A4986/A4987 devices are dual DMOS full-bridge stepper motor drivers with parallel input communication and overcurrent protection. Each full-bridge output is rated up to 35 V and ±2 A. These devices include a fixed off-time pulse width modulation (PWM) current regulator, along with a 2-bit nonlinear DAC (digital-to-analog converter) that allows stepper motors to be controlled in full, half, and quarter step modes.

The PWM current regulator uses the Allegro patented mixed decay mode for reduced audible motor noise, increased step accuracy, and reduced power dissipation. Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Industry standard PHASE, I0, I1 logic inputs are used to control each full-bridge so these motor drivers can replace most existing drivers. The outputs are protected from shorts between motor leads and short-to-ground events, which protect the driver and associated circuitry from thermal damage or flare-ups. Other protection features include thermal shutdown with hysteresis, undervoltage lockout (UVLO), crossover current and over-current protection. Special power-up sequencing is not required.

Allegro’s A4986 and A4987 are offered in several different package options: a 24 contact 4.0 mm × 4.0 mm × 0.75 mm QFN (ES) package, and a 24 lead 7.8 mm × 4.4 mm × 1.2 mm eTSSOP (LP) package. Both packages have exposed thermal pads for enhanced thermal dissipation, and are lead (PB) free with 100% matte tin plated lead frames.

Allegro MicroSystems, LLC is a leader in developing, manufacturing and marketing high-performance semiconductors. Allegro's innovative solutions serve high-growth applications within the automotive market, with additional focus on office automation, industrial, and consumer/communications solutions. Allegro is headquartered in Worcester, Massachusetts (USA) with design, applications, and sales support centers located worldwide. Further information about Allegro can be found at

Editorial Contact:

Stephanie Fennelly
Director - Marketing Communications
Tel: (508) 854-5363

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