A3981: Automotive, Programmable Stepper Driver

The A3981 is a flexible microstepping motor driver with built-in translator for easy operation. It is a single-chip solution, designed to operate bipolar stepper motors in full-, half-, quarter- and sixteenth-step modes, at up to 28 V and ±1.4 A. The A3981 can be controlled by simple Step and Direction inputs, or through the SPI-compatible serial interface that also can be used to program many of the integrated features and to read diagnostic information.

The current regulator can be programmed to operate in fixed off-time or fixed frequency PWM, with several decay modes to reduce audible motor noise and increase step accuracy. In addition the phase current tables can be programmed via the serial interface to create unique microstep current profiles to further improve motor performance for specific applications.

The current in each phase of the motor is controlled through a DMOS full bridge, using synchronous rectification to improve power dissipation. Internal circuits and timers prevent cross-conduction and shoot-through, when switching between high-side and low-side drives.

The outputs are protected from short circuits, and features for low load current and stalled rotor detection are included. Chip-level protection includes: hot and cold thermal warnings, overtemperature shutdown, and overvoltage and undervoltage lockout.

Applications

• Automotive stepper motors
• Engine management
• Headlamp positioning