DMOS Microstepping Motor Drivers offer overcurrent protection. .
May 11, 2010 -
Equipped with built-in translator, Models A4982, A4984, A4985, and A4988 utilize STEP and Direction interface to operate bipolar stepper motors in full, ½, ¼, 1/8, and 1/16 step modes with output drive capacity up to 35 V and ±2 A. Fixed off-time current regulator operates in slow or mixed decay modes, while internal synchronous rectification control circuitry optimizes power dissipation during PWM operation. All packages are lead-free with 100% matte tin-plated lead frames.
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Original Press release
Allegro MicroSystems Inc.
115 N.E. Cutoff, P.O. Box 15036
Worcester, MA, 01615
USA
Allegro MicroSystems, Inc. Announces New DMOS Microstepping Motor Drivers With Overcurrent Protection
Small Footprint in Thermally Efficient Packages
Worcester, MA - Allegro MicroSystems, Inc. announces the expansion of their microstepping motor driver line to include four new devices that require fewer external components and utilize a simple STEP and Direction interface. Allegro's A4982/A4984/A4985 and A4988 devices are complete microstepping motor drivers with a built-in translator for easy operation and overcurrent protection to reduce the rework cost in both manufacturing and normal operations. They are targeted at the office automation market.
These latest devices are 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. They include a fixed off-time current regulator which has the ability to operate in Slow or Mixed decay modes. The translator is the key to the easy implementation of the devices. Simply inputting one pulse on the STEP input drives the motor one microstep. There are no phase sequence tables, high frequency control lines, or complex interfaces to program. The interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.
The chopping control automatically selects the current decay mode (Slow or Mixed). When a signal occurs at the STEP input pin, the device 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 offtime, 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.
Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), crossovercurrent, and over-current protection. Special power-on sequencing is not required.
Allegro's A4982/A4984/A4985 and A4988 are offered in several different package options: a 28 and 32 contact 5 mm × 5 mm × 0.90 mm QFN (ET) package, a 24 contact 4.0 mm × 4.0 mm × 0.75 mm QFN (ES) package, and a 24 lead 7.8 mm × 4.4 mm × 1.2 mm eTSSOP (LP) package. All packages have exposed thermal pads for enhanced thermal dissipation, and are lead (PB) free with 100% matte tin plated lead frames. The 1 A versions of these devices range in price from $1.21 to $1.40 and the 2 A versions range in price from $1.46 to $1.68. All pricing is stated in quantities of 1,000.
About Allegro
Allegro MicroSystems, Inc. is leader in developing, manufacturing and marketing high-performance power and Hall-effect sensor ICs. Allegro's innovative solutions serve high-growth applications within the automotive, communications, computer/office automation, consumer and industrial markets. Allegro is headquartered in Worchester, Massachusetts (USA) with design and applications center located in North and South America, Asia, and Europe. Further information about Allegro can be found at www.allegromicro.com .
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