Power Transmission Engineering Magazine
www.powertransmission.com/articles/2702

Allegro MicroSystems New Motor Driver Completes Product Family

April 4, 2006
Allegro MicroSystems announced a new DMOS full-bride motor driver to complement their parallel input DC motor driver family. Designed for Pulse Width Modulated (PWM) control of DC motors, the A3950 is capable of peak output currents to +/-2.8A and operating voltages to 36 V, according to the company’s press release. The product is targeted at the office automotation, industrial and medical markets. PHASE and ENABLE input terminals are provided for use in controlling the speed and the direction of rotation and torque of a DC motor with eternaly-applied PWM control signals. Internal synchronouis rectification control circuitry reduces power dissipation by switching on appropriate DMOS outputs t effectively short out the body diodes during PWM operation. This internal control technique can reduce output power dissipation by 10-30% in most applications. The A3950 has an over-current protection (OCP) feature that prevents IC damage during motor lead short to supplyand ground conditions. Other internal circuit protction features include thermal shutdown with hystersis, undervoltage lockout of the motor supply and charge pump output and crossover current protection. A diagnostic, open drain output is provded to indicate fault conditions. Brakes