The A5979 is a complete microstepping motor driver with built-in translator. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and sixteenth-step modes, with output drive capability of 40 V and ±2.8 A. The A5979 includes a fixed off-time current regulator that has the ability to operate in slow-, fast-, or mixed-decay modes. This current-decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.
The translator is the key to the easy implementation of the A5979. Simply inputting one pulse on the STEP input drives the motor one step (two logic inputs determine if it is a full-, half-, quarter-, or sixteenth-step). There are no phase sequence tables, high-frequency control lines, or complex interfaces to program. The A5979 interface is an ideal fit for applications where a complex microprocessor is unavailable or overburdened.
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), and crossover-current protection. Special power-up sequencing is not required.
The A5979 is supplied in a thin (<1.2 mm) 28-pin TSSOP with an exposed thermal pad (suffix LP). The package is lead (Pb) free (suffix -T), with 100% matte tin leadframe plating.