September 11, 2012
Worcester, MA – Allegro MicroSystems, Inc. announces a new full-bridge DC motor driver capable of continuous output currents of 1 A and operating voltages from 2.5 to 9 V. Allegro’s A3918 is a new addition to the low voltage family of motor drivers which provides a single full-bridge option to complement the dual full bridge capability found in Allegro’s existing family of devices. Features such as internal PWM current reference allows the user to select the peak chop current with a resistor only. The single supply and simple logic interface makes this an ideal product for single cell Li-ion applications.
The A3918 has a unique design which incorporates a two-stage charge pump that ensures the driver has a low RDS (on) over the entire supply range from 9 V down to 2.5 V. This dramatically improves battery life when battery voltages are low because switches do not become highly resistive due to reduced gate drive. The result is more energy for the load and less heating and power dissipation in bridge. For overcurrent or locked rotor, an internal fixed off-time PWM timer sets a peak current with the addition of a current sense resistor. An overcurrent output flag is provided that notifies the user when the current in the motor winding reaches the peak current.
The A3918 is targeted at low voltage battery operated motor control for consumer, industrial, and medical markets. Applications include point of sale devices, gaming controllers, USB powered devices, digital still cameras, robotics, valve control, and infusion pumps to name a few.
The A3918SESTR-T is provided in a 16-pin, 3 mm × 3 mm, 0.75 mm nominal overall height QFN package, with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating.