Visit the Parker Hannifin Electromechanical Automation web site

Stepper-motor driver IC offers built-in translator

An Allegro Microsystems product story
Edited by the Engineeringtalk editorial team Jan 18, 2002

A new stepper-motor driver IC requires only input one pulse on the step input for the motor to take one microstep: no phase sequence tables, high-frequency control lines or complex interfaces

The new A3977 from Allegro MicroSystems is a stepper-motor driver IC with a built-in translator circuit for easy operation of microstepping functions.

With the new device, it is only necessary to input one pulse on the step input for the motor to take one microstep.

There are no phase sequence tables, high-frequency control lines or complex interfaces to program.

The integration of the microstepping control functions means that the A3977 can run independent1y of a microprocessor, making it ideally suited to applications where complex processors are unavailable or over-burdened.

The new IC is designed to operate bipolar stepper motors in full, half, quarter and eighth step modes, with output drive capability of 35 V and +/-2.5 A.

It includes a fixed off-time current regulator that has the ability to operate in slow, fast or mixed-decay modes, automatically selected by the chopping control.

When a 'step' signal occurs, the A3977 determines if that step results in a higher or lower current in each of the motor phases.

If the change is a higher current, the decay mode is set to slow decay.

If the change is a lower current, the voltage at the 'percentage fast decay' input will set the decay mode.

This current decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.

Internal synchronous rectification control circuitry is provided to improve power dissipation during pulse-width-modulated (PWM) operation.

Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout (UVLO) and crossover current protection.

Special power-up sequencing is not required.

Applications for the A3977 include the office automation, industrial and medical markets.

The inclusion of a 'sleep' mode, coupled with a 3.3-5 V logic supply voltage range, makes the A3977 ideally suited to use in battery-powered equipment.

The circuit is offered in a choice of two power packages: a 44-lead plastic PLCC with a copper batwing tab and a low-profile (1.1 mm) 28L eTSSOP with exposed power tab.

Not what you're looking for? Search the site.

Back to top Back to top

Google Ads

 

Contact Allegro Microsystems

Related Stories

Contact Allegro Microsystems
Newsletter sign up

Request your free weekly copy of the Engineeringtalk email newsletter ...

Visit the Parker Hannifin Electromechanical Automation web site

Browse by category

All suppliers A - Z

A Pro-talk Publication

A Pro-talk publication