A4988 Datasheet, PDF (1/19 Pages) Allegro MicroSystems – DMOS Microstepping Driver with Translator and Overcurrent Protection

A4988
DMOS Microstepping Driver with Translator
and Overcurrent Protection
Features and Benefits
▪ Low R_DS(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
Package:
28-contact QFN
with exposed thermal pad
5 mm × 5 mm × 0.90 mm
(ET package)
Description
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.
Approximate size
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Typical Application Diagram
Microcontroller or
Controller Logic
V_DD
0.22 μF
0.1 μF
0.1 μF
0.22 μF
5 kΩ
VREG ROSC CP1
VDD
CP2
VCP _VBB1
VBB2
SLEEP
STEP
MS1
MS2
MS3
DIR
ENABLE
RESET
VREF
A4988
OUT1A
OUT1B
SENSE1
GND
OUT2A
OUT2B
SENSE2
GND
100 μF
4988-DS