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Allegro MOSFET driver supports 50V supplies

Posted: 26 Mar 2003 ?? ?Print Version ?Bookmark and Share

Keywords:allegro microsystems? a3938? mosfet controller? mosfet driver? transistor driver?

Allegro Microsystems Inc. has introduced the A3938 three-phase power MOSFET controller with high-current gate drive capability that drives discrete n-channel MOSFETs and supports motor supply voltages from 12V to 50V.

Available in 32-lead PLCCs, 36-lead QSOPs, and 38-lead TSSOPs, the device integrates a bootstrapped high-side driver to minimize the external component count required to drive n-channel MOSFETs. Integrated PWM control logic, commutation logic, synchronous rectification, and protection features are also included.

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. A user-selected external RC timing network is also added to set the fixed off-time pulse duration. In addition, the A3938 features an adjustable crossover delay for cross-conduction protection.

Synchronous rectification circuitry minimizes the power dissipation in the discrete MOSFETs, eliminating the need for external power clamp diodes.

The A3938 also provides commutation logic to directly interface Hall sensors configured for 120 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, a motor lead short-to-ground, and thermal shutdown.

Manufactured using the Allegro Bipolar CMOS DMOS 3rd generation (ABCD3) process, the controller is targeted to meet the needs of office automation, industrial, consumer, and medical equipment markets.

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