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High-current gate driver IC for three-phase motors

An Allegro MicroSystems Europe product story

Edited by the Electronicstalk editorial team Dec 22, 2003

The A3938 is a three-phase motor controller IC with high-current gate-drive capability for a wide range of power discrete N-channel MOSFETs and motor supply voltages from 12 to 50V.

The A3938 is a three-phase motor controller IC with high-current gate-drive capability for a wide range of power discrete N-channel mosfets and motor supply voltages from 12 to 50V.

The A3938 integrates a bootstrapped high-side driver to minimise the external component count required to drive the N-channel mosfets.

Integrated pulsewidth-modulation (PWM) control logic, commutation logic, synchronous rectification and sophisticated protection features make the A3938 cost-effective and easy to implement.

The new controller also offers selectable coast or dynamic braking options, allowing the end user to carry out controlled motor operation during a power-loss event.

Internal fixed off-time PWM current control circuitry can be used to regulate the maximum load current to a desired value for speed/torque control.

For added flexibility, a user-selected external RC timing network sets the fixed off-time pulse duration.

In addition, the A3938 features an adjustable crossover delay for crossconduction protection.

The A3938 synchronous rectification circuitry minimises the power dissipation in the discrete mosfets, eliminating the need for external power clamp diodes and allowing for a more economical choice for the N-channel mosfet drivers.

The device includes commutation logic for directly interfacing Hall sensors configured for 120-degree spacing.

The Hall input pins are pulled up to an internally generated 5V reference.

Power mosfet protection features include a bootstrap capacitor charging current monitor, an undervoltage monitor, motor-lead short-to-ground protection, and thermal shutdown.

The A3938 is manufactured using Allegro's new ABCD3 (Allegro bipolar/CMOS/DMOS third-generation) process, and is targeted to meet the needs of the office automation, industrial, consumer and medical equipment markets.

The A3938 is offered in 32-lead PLCC, 36-lead QSOP, or 38-lead TSSOP packages.