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Allegro® Announces New DMOS Microstepping Motor
Driver with Built-In Translator
For Applications with Limited Board Space 
Worcester, MA, January 31, 2007 — Allegro® announces a new addition to their step and direction input family of stepper motor drivers. Allegro's new A4983 is a DMOS microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors in full-, half-, quarter-, eighth, and sixteenth-step modes, with an output drive capacity of up to 35 V and ±2 A. The A4983 includes a fixed off-time current regulator, which has the ability to operate in slow or mixed decay modes. This new motor driver is targeted toward the office automation, industrial and medical markets.
The chopping control in the A4983 automatically selects the current decay mode (slow or mixed). When a signal occurs at the STEP input pin, the A4983 determines if that step results in a higher or lower current in each of the motor phases. If the change is to a higher current, then the decay mode is set to slow decay. If the change is to a lower current, then the current decay is set to mixed (set initially to a fast decay for a period amounting to 31.25% of the fixed off-time, then to a slow decay for the remainder of the off-time). This current decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.
The synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection. Special poweron sequencing is not required.
Allegro’s A4983 is supplied in a 5.0 mm × 5.0 mm × 0.9 mm QFN package with exposed thermal pad (suffix ET). The package is lead (Pb) free (suffix –T), with 100% matte tin plated leadframe.
About Allegro
Allegro MicroSystems, Inc. is a leader in developing, manufacturing and marketing high-performance power and Hall-effect sensor integrated circuits. Allegro's innovative solutions serve high-growth applications within the automotive, communications, computer/office automation, consumer and industrial markets. Allegro is headquartered in Worcester, Massachusetts (USA) with design and applications centers located in North and South America, Asia, and Europe. Further information about Allegro can be found at www.allegromicro.com.
Editorial Contact:
Stephanie Fennelly
Director - Marketing Communications
Tel: (508) 854-5363
sfennelly@allegromicro.com