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High-Performance Power ICs and Hall-Effect Sensors
New Three-Phase Motor Controller with Integrated
3 A, 50 V DMOS Drivers
Technically Advanced Three-Phase Driver IC Solution 
Worcester, MA, January 17, 2002 — Allegro MicroSystems, Inc. introduces its latest generation three-phase brushless DC (BLDC) motor controller / driver IC which features 3 A capable DMOS outputs and on-chip commutation logic. This smaller, more cost effective next-generation solution is based on DMOS technology which offers the following features: pulse-width modulated (PWM) current control of three-phase brushless DC motors, low Rds(on) DMOS outputs, synchronous rectification, 3 V and 5 V logic voltage compatibility and configurable slow, fast and mixed-decay modes.
Synchronous rectification of the integrated on-chip power DMOS outputs is accomplished on-board the IC with no external commands required. Synchronous rectification provides significant improvements in the thermal efficiency of the IC during PWM operation, and eliminates the need for costly external diodes. Low power dissipation is achieved through the efficient use of the DMOS outputs during both the on and off-cycle of the PWM waveform. In addition, Allegro's patented mixed-fast-slow decay mode feature is integrated into this new IC.
The A3936 will operate with motor supply voltages up to 50 V and motor winding currents of 3 A. The A3936 is also compatible with both 5 V and 3 V logic supplies. A tachometer output is provided to enable easy implementation of an external speed control loop. The commutation of the BLDC motor is easily implemented by supplying the A3936 with three Hall sensor inputs.
The IC then processes these inputs and switches the output stages in the proper sequence for either forward or reverse movement of the BLDC motor and load.
Allegro's three-phase motor controller with integrated drivers is targeted to meet the needs of the white goods, process control equipment, medical equipment manufacturers and office automation applications. The A3936 is supplied in a 44-lead PLCC with a copper batwing tab. The power tab is at ground potential and needs no electrical isolation.
Allegro MicroSystems, Inc. is a leading supplier of advanced mixed-signal power semiconductors and Hall-effect sensors targeted toward the office automation, automotive, industrial, and portable electronics markets. With over 2,400 employees, Allegro is headquartered in Worcester, MA and operates multiple wafer-fabrication plants worldwide. Further information on Allegro can be found at www.allegromicro.com.
Editorial Contact:
Stephanie Fennelly
Director – Marketing Communications
Tel: (508) 854-5363
sfennelly@allegromicro.com
Technical Contact:
Bob Brodeur
Strategic Marketing Manager
Tel: (508) 854-5558
bbrodeur@allegromicro.com