A3983 Datasheet | Allegro MicroSystems

Features AND BENEFITS - Low RDS(ON) outputs - Automatic current decay mode detection/selection - Mixed and Slow current decay modes - Synchronous rectification for low power dissipation - Internal UVLO and thermal shutdown circuitry - Crossover-current protection PACKAGE: 24-pin TSSOP with exposed thermal pad (suffix LP) Not to scale DESCRIPTION The A3983 is a plete microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and eighth-step modes, with an output drive capacity of up to 35 V and ±2 A. The A3983 includes 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 A3983. Simply inputting one pulse on the STEP input drives the motor one microstep. There are no phase sequence tables, high frequency control lines, or plex interfaces to program. The A3983 interface is an ideal fit for applications where a plex microprocessor is unavailable or is overburdened. The chopping control in the A3983 automatically selects the current decay mode (Slow or Mixed). When a signal occurs at the STEP input pin, the A3983 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 Continued on the next page… Functional Block Diagram VREG 0.22 µF ROSC 0.1 µF CP1 CP2 Current Regulator Charge Pump STEP DIR RESET MS1 MS2 Translator ENABLE SLEEP PWM Latch Blanking Mixed...