This Step motor controller uses the L297 and L298N driver combination; it can be used as stand alone or controlled by microcontroller. It is designed to accept step pulses at up to 25,000 per second. An on-board step pulse generator can be used if desired (40-650 pps range). Single supply operation is standard
All eight inputs are pulled up to +5V by RP1 (4.7K) and are buffered by 74HC244. The output driver is capable of driving up to 2Amp into each phase of a two-phase bipolar step motor. The motor winding current is limited by means of a 35KHZ-chopper scheme. The potentiometer (R6) is for varying the winding currents. The nature of the chopping scheme eliminates the need for external current limiting resistors on the motor windings; this simplifies connections and increases efficiency.
A useful of this design is the “idle” current reduction mode. The amount of reduction is fixed at approximately 50% from whatever the running current is set at. Similarly, the motor current can be commanded to shut entirely off.
The internal +5V voltages required for operation are derived from the stepper motor supply. The motor supply voltages should be at least 9V, but must never exceed 32V.
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