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General Description
¡¡¡¡Combining low-power CMOS logic with high-current, high-voltage
¡¡¡¡power FET outputs, the Series SLA705xM translator/driver provides
¡¡¡¡complete control and drive for a two-phase unipolar stepper motor
¡¡¡¡with internal fixed off time, pulse-width modulation (PWM) control
¡¡¡¡of the output current in a power multi-chip module (PMCM?).
¡¡¡¡


The CMOS  logic  section  provides  the  sequencing  logic,  direction,
¡¡¡¡full/half-step  control,  synchronous/asynchronous  PWM  operation,
¡¡¡¡and a "sleep" function. The minimum CLOCK input is an ideal fit
¡¡¡¡for applications where a complex ?P is unavailable or overburdened.
¡¡¡¡TTL or LSTTL may require the use of appropriate pull-up resistors
¡¡¡¡to ensure a proper input-logic high. For PWM current control, the
¡¡¡¡maximum output current is determined by the user's selection of a
¡¡¡¡reference  voltage  and  sensing  resistor.  The  NMOS  outputs  are
¡¡¡¡capable of sinking up to 1,2 or 3 A and withstanding 46 V in the off
¡¡¡¡state. Ground-clamp  and flyback  diodes provide protection against
¡¡¡¡inductive transients. Special power-up sequencing is not required.
¡¡¡¡Full-step (2 phase) and half-step operation are externally selectable.
¡¡¡¡Two-phase  drive  energizes  two  adjacent  phases  in  each  detent
¡¡¡¡position (AB-BC-CD-DA). This sequence mode offers an improved
¡¡¡¡torquespeed product, greater detent torque, and is less susceptable to
¡¡¡¡motor   resonance.   Half-step   excitation   alternates   between   the
¡¡¡¡one-phase   and   two-phase   modes   (A-AB-B-BC-C-CD   D-DA),
¡¡¡¡providing an eight-step sequence.

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