Reprap Stepper Driver Stepper Motor Driver A4988/DRV8825

Introduction

       The A4988 is a complete microstep motor driver with built-in converter for easy operation. The product operates bipolar stepper motors in full, half, 1/4, 1/8 and 1/16 step modes with output drive performance up to 35 V and ±1 A. The A4988 includes a fixed off-time current regulator that operates in slow or mixed attenuation mode. The converter is the key to the ease of implementation of the A4988. Simply input a pulse into the "step" input to drive the motor to generate a microstep. No phase sequence table, high frequency control line or complex interface programming is required. The A4988 interface is ideal for applications where complex microprocessors are not available or overloaded.

       The chopping control in the A4988 automatically selects the current decay mode (slow or mixed) during microstep operation. In mixed decay mode, the device is initially set to decay quickly during a partial fixed downtime and then slowly decay during the remaining downtime. Hybrid attenuation current control schemes reduce audible motor noise, increase step accuracy, and reduce power consumption. An internal synchronous rectification control circuit is provided to improve power consumption during pulse width modulation (PWM) operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), and cross current protection. No special power sequencing is required.

        The A4988 is available in a surface mount QFN package (ES) measuring 5 mm × 5 mm and has a nominal overall package height of 0.90 mm with an exposed heatsink for enhanced heat dissipation. The package is lead (Pb)-free (suffix -T) with a 100% matte tin leadframe.

Features and benefits
Low RDS (on) output
Automatic current decay mode detection/selection
Mixed and slow current decay mode
Low power dissipation synchronous rectification
Internal UVLO
Cross current protection
3.3 and 5 V compatible logic power supplies
Thermal shutdown circuit
Ground short circuit protection
Load short circuit protection
Five optional step modes: Full, 1/2, 1/4, 1/8 and 1/16
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DRV8825 vs. 4988 Features:

          1. The maximum current is 2.5A.

          2, the highest support for 32 subdivisions.

          3, 4 layer PCB board, better heat dissipation performance.

          4, the chip internal resistance is smaller, lower heat, better heat dissipation.

parameter:

     Size: 1.5mmX2mm (same as 4988)

     Driven current: 2.5A

     Subdivision: 1, 1/2, 1/4, 1/8, 1/16, 1/32