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Machine Design

Stepper-motor driver IC

The A4979 flexible microstepping motor driver with built-in translator is designed to operate bipolar stepper motors in full, half, quarter, and sixteenth-step modes, at up to 50 V and 1.5 A. The unit is controlled by simple step and direction inputs, or through the SPI-compatible serial interface. Many features, as well as diagnostic feedback, are programmed through the serial port.

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. Phase-current tables are programmed via the serial interface to create unique microstep current profiles to improve motor performance.

Circuit protection includes cross-conduction when switching between high side and low-side drives. Outputs are protected from short circuits. Mixed decay, a key feature in the device, improves low load-current accuracy. Other protection measures include stall detection and hot and cold thermal warnings, overtemperature shutdown, and undervoltage lockout.

Allegro MicroSystems Inc.
115 Northeast Cutoff
Worcester, MA 01606
(508) 853-5000

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