The OFS350 series of open-frame ministepping drives offer a 3.5A output with a resolution of 400-12,800 steps/rev, a step phase sequencer with MOSFET three-state switching amplifiers and opto-isolated circuits. The amplifier regulates motor current by chopping at a constant, inaudible frequency. Phase current is selected from 32 levels by a DIP switch, which also controls the microstepping resolution. The OFS350-DRI ministepper drive accepts industry standard step and direction command signals from an external control source. The OFS350-OSC drive additionally adds an on-board clock source and includes five optically isolated inputs, external speed control, tach output, and internal pots for accel/decel rate along with high- and low-speed range selection. Both versions of the drive include a selectable automatic feature to lower the motor current by 50% whenever the motor is left at rest for more than one second. There is also a switch-selectable self test mode that rotates the motor one-half a revolution in each direction at 100 steps per second.

OFS350 Open Frame Ministepper Drive - Common Features:
• Drive Input Supply : 12...42VDC
• Output Current : 2.47 Arms / 3.5 Apk
• Resolution : 400, 1000, 2000 and 12,800 steps/rev
• Switch selectable idle current reduction, 0 or 50%
• Optically Isolated 5VDC Inputs for Step, Direction and Enable (OFS350-DRI)
• Optically Isolated 5–12 VDC Inputs (OFS350-OSC)
• Enable Input (to turn off current to the motor)
• Self Test (switch selectable)
• Screw Terminal Connectors.
• MOSFET, Dual H-Bridge, Inaudible PWM Amplifier
• 3 State, Pulse Width Modulated Current Control (switching at 20–30 KHz)
• Drives 4, 6 or 8 Lead / Size 11, 14, 17, 23 or 34 Step Motors
• CE compliant

OFS350-OSC Specific Features:
• Run Input : directs drive to run or stop
• Direction Input : sets direction of rotation
• Speed Input : selects high speed (25rps) or low speed (5rps) range
• Wiper Input : 0–5V analog for external speed signal, pot or joystick
• Tach Output : 5–24V optically isolated, 100 pulses per revolution
• Three Internal Trimmer Pots : - Accel/Decel (1–250 rev/sec/sec) / -  Low Speed (0–5 rps) / - High Speed (0–25 rps)
• External Speed, Pot or Joystick 3 Terminal Type, 1k–10k ohms