Machine Design

Motor driver

The A3918 is a full-bridge dc-motor driver capable of 1-A continuous output and 2.5 to 9-V operating voltage. An internal PWM current reference lets users select the peak chop current with a resistor only. The single supply and simple logic interface makes the driver suitable for single-cell Li-ion applications.

The driver uses a two-stage charge pump to ensure it has a low RDS (on) over the entire supply range from 9 down to 2.5 V. This dramatically improves battery life when voltages are low because switches do not become highly resistive due to reduced gate drive, resulting in 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 notifies users when the current in the motor winding reaches the peak current.

Allegro MicroSystems
115 Northeast Cutoff
Worcester, MA 01606
(508) 853- 5000

© 2013 Penton Media, Inc.

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