The PDO2035 step motor driver contains a power supply, full and half step phase sequencer, two switching amplifiers, a digital ramping pulse generator and optoisolation circuits. This driver also includes a power saving feature to automatically lower motor current anytime the motor is left at rest for more than one second. The amplifiers regulate motor current by chopping at a constant, inaudible frequency. Phase current is selected from 16 levels by a dip switch. Full or half step operation is also selected by the dip switch.

The internal oscillator is selected by a dip switch. In oscillator mode, the pulse input becomes a run/stop signal: when this signal is set low, the motor accelerates to a preset speed and slews. Raising the input high (to 5 volts) causes the driver to decelerate to rest. Two oscillator speed ranges are provided: 10 - 1200 steps/sec and 100 - 12000 steps/sec. The digital oscillator derives it's timing from a quartz crystal for low drift and repeatable ramps. The speed of the oscillator can be set by an on-board potentiometer, or an external pot, or an external 0-5 volt analog signal.

The PDO2035 is built on an aluminum heat transfer plate, and is surrounded by a sturdy, ventilated steel enclosure.