New Industry Products

Allegro Debuts A3938 Power MOSFET Controller

March 30, 2003 by Jeff Shepard

Allegro MicroSystems Inc. (Worcester, MA) introduced a new three-phase power MOSFET controller with high-current gate drive capability that drives a wide range of power discrete n-channel MOSFETs and supports motor supply voltages from 12V to 50V. The A3938 integrates a bootstrapped high-side driver to minimize the external component count required to drive the n-channel MOSFETs. The A3938 is targeted to meet the needs of the office automation, industrial, consumer and medical equipment markets.

The A3938 offers selectable coast or dynamic braking options, allowing the end user controlled motor operation during a power-loss event. The A3938 synchronous rectification circuitry minimizes the power dissipation in the discrete MOSFETs, eliminating the need for external power clamp diodes and allows for a more economical choice for the n-channel MOSFET drivers. Internal, fixed, off-time, pulse-width modulation 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 cross-conduction protection.

The A3938 is offered in the 32-lead PLCC, 36-lead QSOP, and 38-lead TSSOP packages. All packages have a 14 to 16 week lead time to market, and are priced at $3.11 per part in quantities of 10,000.