Sensorless Brushless DC Motor Drive Constant Torque Across Operational Speed Range, Excellent Energy Efficiency Design, Sensorless BLDC Motor Drive Advantage, Protection for Under Over Voltage, Over Current, Polarity Reversal, Speed and Current Control Loop for Smooth Operation from Low To High Speeds, 4-20 mA Output (Speed Readout) - Optional. Pwm In for Setting Ref Speed and Pwm out for Speed Readout.