DMOS MICROSTEPPING MOTOR DRIVER WITH BUILT-IN TRANSLATOR

Description

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 offtime 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 translator is the key to the easy implementation of the A4983. 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 A4983 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened. 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 x 5.0 mm x 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. It is priced at $1.87 in quantities of 1,000 and has a 10-12 week typical lead-time to market.

Specs

* ±2.5 A, 35 V output rating * Low rDS(ON) outputs, 0.45 Ω source, 0.36 Ω sink typical * Automatic current decay mode detection/selection * 3.0 to 5.5 V logic supply voltage range * Mixed, fast, and slow current decay modes * Home output * Synchronous rectification for low power dissipation * Internal UVLO and thermal-shutdown circuitry * Crossover-current protection
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