The A4975 is designed to be based onMicrostepping mode driveOne winding of a bipolar stepper motor. The continuous output current is rated at ±1.5 amps and can operate up to 50 volts. Internal pulse-width modulation (PWM) current control and an internal three-bit nonlinear digital-to-analog converter allow the device to control motor current in full-step, half-step, quarter-, or one-eighth step (microstep) mode. Nonlinear increments minimize the control circuitry required for microstepping. Microstepping improves step resolution and reduces torque variations and resonance issues at low speeds.
The internal circuitry decidesPWM current control circuitryOperating modes: slow (recycling) current attenuation mode, fast (regenerative) current attenuation mode, or mixed current decay mode. In hybrid current decay mode, the shutdown time is divided into two time periods: fast current decay and fixed shutdown time with slow current decay. Combined with user-selectable current sense resistor and reference voltage, digitally selectable output current ratio; Slow, fast, or mixed current attenuation modes provide users with a variety of different motor controls.
Internal circuit protection includes thermal shutdown with delay, transient suppression diodes, and crossover current protection. No special power-on sequencing is required. The A4975 is available in two power packages: a 16-pin dual in-line plastic package with copper heatsink (suffix B) and a 16-pin plastic SOIC with an internal fuse pin (suffix LB). Both packages have heat-dissipating pins and are grounded, eliminating the need for electrical isolation. Both packages are lead (Pb) free and feature 100% matte tin coated leadframes.
- ±1.5 amps continuous output current
- 50 volt output voltage rating
- Internal PWM current control
- Three-bit nonlinear DAC
- Fast, fast/slow hybrid, and slow current decay modes
- Internal thermal shutdown circuitry
- Crossover current and UVLO protection