A498x Motor Driver Family

By Allegro MicroSystems, LLC 94

A498x Motor Driver Family

Allegro's A4982 / A4984 / A4985 and A4988 devices are complete microstepping motor drivers with a built-in translator for easy operation and overcurrent protection. They 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. These devices 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 A4986 / A4987 devices are dual DMOS full-bridge stepper motor drivers with parallel input communication and overcurrent protection. Each full-bridge output is rated up to 35 V and ±2 A. These devices include a fixed off-time pulse width modulation (PWM) current regulator, along with a 2- bit nonlinear DAC (digital-to-analog converter) that allows stepper motors to be controlled in full-, half-, and quarter-step modes. The PWM current regulator uses the Allegro patented mixed decay mode for 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. Industry standard PHASE, I0, I1 logic inputs are used to control each full-bridge so these motor drivers can easily replace most existing drivers.