Dual full-bridge motor driver IC drives two DC motors

7th June 2007

ES Admin

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The new A3995 from Allegro MicroSystems Europe is a DMOS full-bridge motor driver IC designed to control two DC motors at currents of up to 2.4 A and drive voltages of up to 36 V.The new device operates over a logic supply voltage range from 3 to 5.5 V, and incorporates two independent fixed off-time PWM (pulse-width modulation) current regulators that operate in either fast or slow decay mode. The use of fixed off-time PWM current control reduces external component count and limits the maximum current to help prevent motor and IC damage.

Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation, and 'phase', 'enable' and 'mode' inputs are provided for use in controlling the speed, torque, direction and brake and coast functions of a DC motor.

High and low side synchronous rectification reduces power dissipation and can eliminate the need for expensive Schottky diodes. The low-resistance DMOS outputs also reduce power dissipation, and allow the device to operate with higher average output currents because of the lower die temperature
rise.

Protection features include thermal shutdown with hysteresis, undervoltage lockout and crossover current protection. Special power-up sequencing is not required.

This new motor driver is targeted at the office automation and industrial markets where there is a demand for compact, power-efficient solutions for controlling multiple motors. By integrating two motor drivers in one package the A3995 is more cost effective than most discrete IC motor drivers with
similar ratings. The compact package is an advantage in applications where PC board space is at a premium.

The A3995 is supplied in a lead (Pb) free 36-lead QFN package with exposed power tab for enhanced thermal dissipation. It has a 6 mm ( 6 mm footprint and 0.90 mm nominal height.