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HIGH-CURRENT GATE DRIVER IC FOR 3-PHASE MOTORS
16 December 2003 - Allegro MicroSystems, Inc.,

Allegro MicroSystems has introduced a new 3-phase motor controller IC with high-current gate-drive capability. The new A3938 drives a wide range of power discrete n-channel MOSFETs and supports motor supply voltages from 12 V to 50 V. The A3938 integrates a bootstrapped high-side driver to minimise the external component count required to drive the n-channel MOSFETs. Integrated pulse-width-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 cross-conduction 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° spacing. The Hall input pins are pulled up to an internally generated 5 V reference.

Power MOSFET protection features include a bootstrap capacitor charging current monitor, an under-voltage 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.

http://www.allegromicro.com

About: Allegro MicroSystems, Inc.,
Allegro MicroSystems, Inc. provides innovative system-level solutions in the design and manufacture of advanced mixed-signal Hall-effect sensor and analog power ICs serving high-growth applications worldwide within the Automotive Electronics, Office Automation, Industrial and Portable Electronics markets. We offer cutting-edge technology, a commitment to quality, and innovative solutions. Our design and manufacturing teams are ready to work diligently with you to support your needs.

What Sets Allegro Apart?
Allegro develops total solutions for virtually all power IC and sensing applications. We provide vertically integrated mixed-signal ICs, adding more components and greater functionality. Allegro's line has extensive product breadth and depth, with standard "plug and play" products.

The only Hall-effect manufacturer with BiCMOS design capabilities.
BCD (Bi-polar, CMOS, DMOS) products offer greater efficiency, and control.
Allegro's Mission
Allegro MicroSystems, Inc. will remain a worldwide leading supplier of analog integrated circuits to the automotive, portable electronics, office automation and industrial market segments through focused efforts to

Provide value to our customers
Offer technically advanced products
Achieve growth and profitability
Challenging the organization to continuously improve, and
Maintain a positive work environment for our associates
Allegro's Businesses
Allegro is currently organized into two technology-defined groups. These groups are paving parallel paths of expansion, up-integration, and diversification by entering or broadening into markets with higher growth.

The Sensor group produces Hall-effect sensors offering contactless switching for applications such as direction-detection, geartooth, linear, position, and speed sensing for automotive, industrial, consumer, and portable electronics.

The IC group produces power ICs for motor drives, motor control and power interface. Allegro's ICs are used in office automation (particularly printers), industrial, automotive and portable electronics markets.

Allegro's Technology
Allegro is a technology leader, an up-integrated developer of total solutions for multiple power ICs and sensing applications. The product success is based on extensive semiconductor expertise and merged technologies capabilities. Allegro's products are built with design features that include high-current outputs, very wide operating temperature range, reversed power supply, and transient protection, and output short-circuit safety functions.

Mixed-signal processing capabilities allow precision analog circuitry to be used in harsh operating conditions. Allegro has strategically positioned itself in the analog segment, and emphasizes application-specific, market-driven products with high technology content. These include bipolar, CMOS, and DMOS technologies, as well as merged technologies such as BiCMOS (bipolar + silicon-gate CMOS), BCD (bipolar + CMOS + DMOS), and DABIC (digital + analog + BiCMOS). The company can and does combine any two or all three of its product disciplines into a single monolithic chip to deliver powerful system-level solutions. These solutions are sold under Allegro's trademark "ABCD5" (Allegro's BiCMOS, CMOS and DMOS).

Allegro's Products and Solutions
Allegro manufactures Hall-Effect Sensors, Motor Driver ICs, Power Conversion Devices, Power Interface ICs, and Power Management ICs. Standard Product Development resources are focused on introduction of the next generation mixed-signal product solution. The Company focuses on power output products that add value to overall systems. The end result are products that offer higher levels of function integration, lower system stand-by power, and lower output saturation voltages.

SENSORS
Allegro's sensors are based on Hall-effect technology, which allows contact-less sensing, (devoid of mechanical wear) of either an external magnet or a ferrous object. Specifically, Hall-effect sensors are used for contactless switching, position sensing, speed sensing, linear sensing and gear-tooth sensing. Currently, the auto market is where the most Allegro sensor applications can be found, applications within engine, transmission, emissions, suspension, steering, braking, cooling, doors/windows/seats, airbags, and other systems. Recent strict emission regulations on boat engines and other small engines will create demand for like products in these markets.

For Hall-effect sensors, a dilemma can sometimes arise because electronic design engineers are not comfortable with the necessary IC components and mechanical design engineers are not comfortable with the magnets. In these cases, the up-integration of components and sub-assemblies, by Allegro, combining both aspects, is the answer.

POWER ICs
Power IC applications in office automation are led by the motor driver needs of various printers (inkjet for PCs, vending, P-O-S, etc.), scanners, projectors, fax machines, copiers and multifunction peripherals.

Driver and controller ICs are also produced by Allegro for fractional horsepower dc, stepper and brushless dc motors in the industrial and automotive markets. BCD technology gives Allegro an advantage in higher power applications and allows expansion in existing markets and associated applications such as large tape drives, automotive blowers, power steering motors, and factory automation.

Power Interface ICs are used in industrial and automotive applications such as relays and solenoids, and LED and VF displays. Display drivers include those used in automotive, medical, scales and signs.

Manufacturing
Allegro understands that investment in manufacturing is critical to long-term success. The ongoing investment in IC fabrication, packaging, testing, and handling facilities, both in the US and abroad, ensures that Allegro is poised to meet the needs of all customers. The Company is committed to manufacturing integrated circuits with the highest standards of quality, reliability and service.

Allegro Facts
Allegro, operating under that name for the past decade, is the successor to Sprague Semiconductor Group, with 40 years combined experience in the semiconductor industry. With over 2,500 employees worldwide, Allegro is headquartered in Worcester, MA, where design, manufacturing, test, marketing and customer service are located in a 250,000 sq. ft. facility. The Company also has manufacturing plants in New Hampshire, Pennsylvania, and the Philippines, as well as sales, design and marketing offices in Scotland, UK, France and Argentina. Sales are balanced worldwide throughout North and South America, Europe, Japan and Asia-Pacific, with products sold primarily to OEMs through a strong worldwide sales channel that includes a direct sales force, manufacturers representatives and distribution. The Company is ISO 9000 and QS-9000 registered and has received quality awards from leading manufacturers worldwide, including IECQ manufacturer's approval.

Allegro is a wholly owned subsidiary of Sanken Electric Company, Ltd., a billion dollar company who manufactures semiconductors, discretes, LEDs, and switch mode power supplies, with headquarters in Saitama, Japan. The two companies jointly develop and market leading-edge products in the areas of power management and motion control. This enables both organizations to fully utilize the company's worldwide strengths and resources for the benefit of our customers.


More News:
  • For December 2003
  • From Allegro MicroSystems, Inc.,
  • For Drives and Controls

 

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