Allegro's A4942 is a three phase sensorless brushless DC motor driver designed for fan and blower applications. Key applications include industrial and office automation fans such as those found in network servers. Key advantages include sensorless commutation, closed loop speed control, minimum and maximum speed settings, soft switching, adjustable soft start, adjustable phase advance, over current PWM protection, and small 20L 4 mm x 4 mm QFN package (ES).