A4988: DMOS Microstepping Driver with Translator and Overcurrent Protection

The A4988 is a complete microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors in full-, half-, quarter-, eighth-, and sixteenth-step modes, with an output drive capacity of up to 35 V and ±2 A. The A4988 includes a fixed off-time current regulator which has the ability to operate in slow or mixed decay modes.

The translator is the key to the easy implementation of the A4988. Simply inputting one pulse on the STEP input drives the motor one microstep. There are no phase sequence tables, high frequency control lines, or complex interfaces to program. The A4988 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.

During stepping operation, the chopping control in the A4988 automatically selects the current decay mode, Slow or Mixed. In Mixed decay mode, the device is set initially to a fast decay for a proportion of the fixed off-time, then to a slow decay for the remainder of the off-time. Mixed decay current control 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 PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection. Special power-on sequencing is not required.

The A4988 is supplied in a surface mount QFN package (ES), 5 mm × 5 mm, with a nominal overall package height of 0.90 mm and an exposed pad for enhanced thermal dissipation. It is lead (Pb) free (suffix –T), with 100% matte tin plated leadframes.

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Allegro MicroSystems, LLC (Allegro & Sanken Semiconductors) 
Phone: 267-373-9862
Fax: 215-957-5585
Cindy Painter, Email: cpainter@allegromicro.com

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  • Features and BenefitsFeatures and Benefits
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  • Low RDS(ON) outputs
  • Automatic current decay mode detection/selection
  • Mixed and Slow current decay modes
  • Synchronous rectification for low power dissipation
  • Internal UVLO
  • Crossover-current protection
  • 3.3 and 5 V compatible logic supply
  • Thermal shutdown circuitry
  • Short-to-ground protection
  • Shorted load protection
  • Five selectable step modes: full, 1/2, 1/4, 1/8, and 1/16

The A4988 is supplied in a surface mount QFN package (ES), 5 mm × 5 mm, with a nominal overall package height of 0.90 mm and an exposed pad for enhanced thermal dissipation. It is lead (Pb) free (suffix –T), with 100% matte tin plated leadframes.

ET QFN with exposed pad 28 lead

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Product Image Functional Block Diagram Typical Application

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Compliant
Part Composition /
RoHS Data
Comments Samples Check
Distributor Stock
A4988SETTR-T 28-lead QFN -20°C to 85°C Yes View Data Contact your
local sales rep
Check stock
APEK4988SET-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Check stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.

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