2.5A Bipolar Stepper Motor Driver using A3979

The tiny board designed using A3979 IC from ALLEGRO which is complete micro stepping driver with built in translator. The translator is the key to the easy implementation of the A3979. It allows the simple input of one pulse on the STEP pin to drive the motor one micro step, which can be either a full step, half, quarter, or sixteenth, depending on the setting of the MS1 and MS2 logic inputs. There are no phase-sequence tables, high-frequency control lines, or complex interfaces to program. The A3979 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.

Features

• CN1 Motor Supply Input Up to 30V DC (35V Maximum)
• Load 2.5A
• Logic Supply 3.3V to 5V DC
• CN3 Bipolar Stepper Motor Connections
• CN2 Logic Supply 5V & Signal Inputs
• J1-MS2 & J2-MS1 Micro-Stepping FULL, HALF, Quarter, Sixteenth
• J3, J4 Option Replacement for PR1 Jumper Type Current Setting
• D1 Logic Power LED
• REF (PR1) Current Adjust 0-2V

PFD (PR2)

When A step input signal commands a lower output current then the previous step, it switches the output current decay to either slow, fast or mixed decay mode, depending on the voltage level at the PFD input. If the voltage at PFD input is greater than 0.6xVCC, then slow decay mode selected, if the voltage on PFD input is less than 0.21xVCC then the fast decay mode selected, when VPFD is between these two levels mixed decay mode selected.

Schematic

Parts List

Connections

Photos

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