Date: 16/09/2012

1 Ampere, DC motor driver operates from a low voltage of 2.5 Volts

Motion control IC expert Allegro MicroSystems has announced a new full-bridge DC motor driver capable of continuous output currents of 1 Ampere and operating voltages from 2.5 to 9 V. Allegro’s A3918 features internal PWM current reference to allow the user to select the peak chop current with a resistor only. The single supply and simple logic interface makes this a good choice for single cell Li-ion applications.

Allegro explains: the A3918 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.