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DUAL DMOS FULL-BRIDGE MICROSTEPPINGPWM MOTOR DRIVERDesigned for pulse-width modulated (PWM) current control of bipolarmicrostepping stepper motors, the A3972SB is capable of conTInuous outputcurrents to ±1.5 A and operaTIng voltages to 50 V. Internal fixed off-TImePWM current-control TIming circuitry can be programmed via a serial interfaceto operate in slow, fast, and mixed current-decay modes.The desired load-current level is set via the serial port with two 6-bit linearDACs in conjunction with a reference voltage. The six bits of control allowmaximum flexibility in torque control for a variety of step methods, frommicrostepping to full-step drive. Load current is set in 1.56% increments of themaximum value.Synchronous rectification circuitry allows the load current to flow throughthe low rDS(on) of the DMOS output driver during the current decay. Thisfeature will eliminate the need for external clamp diodes in most applications,saving cost and external component count, while minimizing power dissipation.Internal circuit protection includes thermal shutdown with hysteresis,transient-suppression diodes, and crossover-current protection. Special powerupsequencing is not required.The A3972SB is supplied in a 24-lead plastic DIP with a copper batwingpower tab. The power tab is at ground potential and needs no electricalisolation. The lead (Pb) free version has 100% matte tin leadframe plating.
