Mechanical and Electromechanical Systems

Allegro A3977 Microstepping Stepper Motor Control IC Review

Posted: October 1st, 2010 | Author: Tom Scarince | Filed under: Motor Control, Stepper Motors | Tags: , , | No Comments »

Configuration: Dual H-Bridge w/ microstepping translator
Applications: Stepper Motor
Current (peak): 2.5 amps
Voltage (max): 35V
Short circuit protection: No
Built-in chopper current limitation: Yes, Full and half stepping, 4 and 8 microsteps
Interface: Step and Direction

A3977 PCB

A3977 PCB

With dual h-bridges and a built-in translator, DAC and chopper circuits, the A3977 is a nearly complete microstepping stepper motor controller on a single chip.  With the addition of a handful of external passive components, this IC is ready to accept step & direction signals from a pulse generator, microcontroller, indexer or CNC controller.  Each pulse applied to the Step input rotates the motor one microstep forward or reverse, depending on the state of the Direction input. 

 


Understanding Mixed Decay and the Allegro A3977 PFD Percent Fast Decay Feature

Posted: April 16th, 2009 | Author: Tom Scarince | Filed under: Stepper Motors | Tags: | No Comments »

This article explains why you might want to use mixed decay and how it is implemented in the A3977’s current chopper PWM scheme with the percent fast decay (PFD) pin. 

Read the rest of this entry »