The A3989 can operate at voltages up to 36 V while driving a bipolar stepper motor at up to 1.2 A and a DC motor at up to 2.4 A. The A3989 includes a fixed off-time pulse-width modulation (PWM) current control regulator. The stepper motor driver features dual 2-bit nonlinear DACs (digital-to-analog converters) that allow stepper motor control in full, half, and quarter step modes. DC motors can be controlled using standard phase and enable signals. Fast or slow current attenuation can be selected via the mode pin. PWM current regulators use Allegro's® patented hybrid attenuation mode to reduce audible motor noise, increase step accuracy, and reduce power dissipation.
Internal synchronizationRectifier control circuitReduces power consumption during pulse-width modulation (PWM) operation.
Protection features include thermal shutdown due to hysteresis, undervoltage lockout (UVLO), and crossover current protection. No special power-up sequencing is required.
The A3989 is available in Pb-free 6 mm × 6 mm × 0.9 mm, 36-lead QFN packages with exposed power sheets for enhanced thermal performance. Lead-free package with 100% matte tin leadframe plating.
- 36 volt rated output voltage
- 2.4 A DC motor driver
- 1.2 A bipolar stepper driver
- Synchronous rectification
- Internal Undervoltage Lockout (UVLO)
- Thermal shutdown circuit
- Crossover current protection
- Ultra-thin QFN package