Allegro MicroSystems, Inc. (www.allegromicro.com) has unveiled the all-new A4975, a motor driver IC that can drive a single winding of a bipolar stepper motor in microstepping mode. Its output has been rated for operating voltages of up to 50 V and for continuous output current of up to ±1.5 A.
Allegro’s A4975 seamlessly combines an internal three-bit non-linear digital-to-analog converter with an internal pulse width modulated (PWM) current control, enabling it to control the motor current in eighth-, quarter-, half-, or full-step (microstepping) modes. Its nonlinear increments reduce the number of control lines required for microstepping. Reducing resonance problems and torque variation at low speed, microstepping also offers increased step resolution, making the device ideally suited for office automation as well as industrial markets with end applications including scanners, printers and copiers.
The internal circuitry of the A4975 indicates whether its PWM current-control circuitry functions in a fast (regenerative) current-decay mode, slow (recirculating) current-decay mode or in mixed current-decay mode. Combining user-selectable current-sensing resistor with digitally selected output current ratio, reference voltage and mixed, slow, or fast current-decay modes delivers a wide, variable range of motor control.
Its internal circuit protections feature an undervoltage monitor, thermal shutdown with hysteresis and crossover-current protection.
Available in two selectable power packages, the motor driver IC also eliminates the need for special power-up sequencing. Lead (Pb) free, both package styles are offered in 100 percent matte tin leadframe plating and require no electrical isolation as its thermally enhanced pins are at ground potential.