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Stepper motor drivers feature auto start function

Posted: 18 Apr 2007 ?? ?Print Version ?Bookmark and Share

Keywords:stepper motor driver? stepper motors? continuous velocity?

AMI Semiconductor added enhancements to their family of single-chip stepper motor driver and control ICs. The new features include a facility for running stepper motors at a continuous velocity and an automatic start function that allows a stepper motor to start automatically when powered up.

Continuous, defined velocity
The enhanced features have been incorporated into the AMIS-30624, a device designed for the control of remote and multiple axes positioning applications via high-level position instructions on the I?C bus. RunVelocity is the I?C command that makes the stepper motor run at a continuous, defined velocitya feature that's useful for pumps, where flow needs to be controlled very accurately. Velocity can be changed "on the fly" under user or software control. Designers, looking to allow a stepper motor to act in the same way as a brushed DC motor, can select an "automatic start" function. When selected, the motor will start running as soon as power is applied, based on parameters loaded from an internal non-volatile memory bank.

Designed for mechatronic applications, the AMIS-30624 is suited for designs where the motor controller IC is a peripheral device, located next to a host MCU on a PCB. Sensorless stall-detection functionality allows designers to implement silent, yet accurate, position calibration and semi-closed loop operation when approaching mechanical end stops. An integrated "Motion Qualification Mode" helps application developers select a set of motion parameters including torque and acceleration-deceleration profile. As a result, noise and vibration at end-stops can be eliminated, and motion control accuracy and reliability improved, without the need for optical encoders, position sensors or software algorithms.

Target applications
In addition to pumps, target applications for the AMIS-30624 include surveillance camera control, professional lighting equipment, industrial "X,Y,Z" tables, manufacturing robots and building automation. The device will operate at temperatures from -40C to 125C and can deliver programmable currents of up to 800mA at 125C. The on-chip position controller provides the micro-stepping feature and is configurable for different motor types, positioning ranges and parameters including speed, acceleration and deceleration. A power-down supply current of under 100?A provides minimum power consumption in standby mode.

The device is available at $4.85 each in 5,000-piece quantities.

- Emily Gleason

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