Full-Bridge PWM Micro-stepping Driver Cuts Power Dissipation

The A4975 motor driver IC is designed to drive one winding of a bipolar stepper motor in a micro-stepping mode. The driver’s outputs are rated for continuous output currents to ±1.5 A and operating voltages to 50 V. Internal PWM current control combined with an internal three-bit nonlinear digital-to-analog converter allows the motor current to be controlled in full-, half-, quarter-, or eighth-step micro-stepping modes. Nonlinear increments minimize the number of control lines necessary for micro-stepping. Micro-stepping provides increased step resolution, and reduces torque variations and resonance problems at low speed. This new device is targeted at the office automation and industrial markets with specific end applications to include printers, scanners and copiers. The A4975 is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs (suffix B), and a 16-lead plastic SOIC with internally fused pins (suffix LB). For both package styles, the thermally enhanced pins are at ground potential and need no electrical isolation. Both packages are lead-free, with lead-frame plating of 100% matte tin. The A4975SB-T and A4975SLBTR-T are priced at $1.70 each/1000.ALLEGRO MICROSYSTEMS INC.