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High-Performance Power ICs and Hall-Effect Sensors
Allegro MicroSystems, Inc. Announces Three Phase
Pre-Drive IC Targeted at High Power Automotive and Industrial Motors
New Gate-Driver IC 
Worcester, MA, October 30, 2002 — Allegro MicroSystems, Inc. announces the release of the A3935, a new power MOSFET pre-driver IC for large three-phase brushless DC (BLDC) motors. The IC has been designed to accommodate the demanding needs of the Automotive and Industrial/Factory Automation markets. With maximum operating temperature specifications to +135°C the A3935 is designed to operate in the harsh under-hood environment of automotive applications such as engine cooling and electronic power steering (EPS).
The A3935 has an on-board boost converter designed to allow operation of the pre-driver IC in low-battery conditions while still maintaining adequate gate drive voltage. The A3935, with an operating voltage range from 7 V to 40 V, is a good choice for systems where either 12 V or 24 V batteries are in use. The A3935 features an adjustable over-voltage (OVSET) feature, which protects the IC if motor supply voltages exceed a user set voltage with a range of 19.4 V to 40 V.
Additional automotive and industrial features include: fault reporting and diagnostics including short-to-battery and short-to-ground detection using drain-to-source (Vds) monitoring of the external N-channel MOS transistors. Three fault-output reporting pins are used to help the system controller diagnose and decode the cause of the fault and take the appropriate action.
Independent control of each external transistor is possible by using the six parallel input pins of the A3935. This individual control allows maximum system flexibility and allows the implementation of sinusoidal control of the BLDC motor.
In addition, the A3935 integrates a current sense amplifier with fixed gain and offset, which provides easy implementation of low-side current sensing using an external series shunt resistor.
The A3935 is manufactured using Allegro's ABCD3 (Allegro Bipolar CMOS DMOS 3rd generation) process, and is supplied in either a 44-lead plastic PLCC with four copper batwing tabs for maximum heat dissipation or in a 36-lead QSOP package.
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