DMOS Microstepping Driver Has Built-in Translator

30 March 2016

Allegro MicroSystems, LLC has introduced an integrated bipolar stepper motor driver IC with built-in translator for easy operation. Allegro’s A5984 is designed to operate bipolar stepper motors from full-step up to 1/32 step modes that are selectable by MSx logic inputs. This device has an output drive capacity of up to 40 V and ±2 A and operates with a single supply.
Allegro’s A5984 DMOS microstepping driver. (Source: Allegro Microsystems) Allegro’s A5984 DMOS microstepping driver. (Source: Allegro Microsystems)
The motor driver IC introduces a proprietary Adaptive Percent Fast Decay (APFD) algorithm to optimize the current waveform over a wide range of stepper speeds and stepper motor characteristics. This algorithm adjusts, on the fly, the amount of fast decay with the goal of maintaining current regulation while minimizing current ripple. This adaptive feature improves performance of the system, reducing noise and vibration while increasing step accuracy.
The translator is the key to the easy implementation of the A5984. Simply inputting one pulse on the STEP input drives the motor one micro-step. There are no phase sequence tables, high-frequency control lines, or complex interfaces to program. The A5984 interface is suited for applications where a complex microprocessor is unavailable or is overburdened.
Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes overcurrent protection, thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection.
The A5984 is supplied in three surface mount packages. Two QFN packages include a 4 mm × 4 mm, 0.75 mm high ES package and a 5 mm × 5 mm × 0.90 mm ET package. The part is also available in a 24-pin TSSOP LP package. All three packages have exposed pads to enhance thermal dissipation and are lead (Pb) free with 100% matte-tin-plated lead frames.
The A5984 is priced from $1.29 each in quantities of 1,000, depending on the version ordered.

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