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| A3987 Datasheet, PDF (1/13 Pages) Allegro MicroSystems – DMOS Microstepping Driver with Translator | |||
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A3987
DMOS Microstepping Driver with Translator
Features and Benefits
⪠Low RDS(on) outputs
⪠Short-to-ground protection
⪠Shorted load protection
⪠Automatic current decay mode detection/selection
⪠Mixed and slow current decay modes
⪠Synchronous rectification for low power dissipation
⪠Internal UVLO and thermal shutdown circuitry
⪠Crossover-current protection
Package: 24 pin TSSOP with exposed
thermal pad (suffix LP)
Approximate scale
Description
The A3987 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, and sixteenth step
modes, with output drive capability of 50 V and ±1.5 A. The
A3987 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
A3987. Simply inputting one pulse on the step input drives the
motor to take one microstep. There are no phase sequence tables,
high frequency control lines, or complex interfaces to program.
The A3987 interface is an ideal fit for applications where a
complex microprocessor is unavailable or over-burdened.
The A3987 chopping control automatically selects the current
decay mode (slow or mixed). When a STEP signal occurs,
the translator determines if that step results in a higher or
lower current in each of the motor phases. If the change is to
a higher current, then the decay mode is set to slow decay. If
the change is to a lower current, then the decay mode is set to
30.1% fast decay. This current decay control scheme results
in reduced audible motor noise, increased step accuracy, and
reduced power dissipation.
Continued on the next pageâ¦
Typical Application Diagram
Microcontroller or
Controller Logic
10 μF
5 kΩ
0.22 μF
VREG
VDD
0.1 μF
X7R
CP1
CP2
VCP
ROSC
A3987
STEP
DIR
SLEEP/RESET
ENABLE
MS1
MS2
REF
VBB1
VBB2
OUT1A
OUT1B
SENSE1
OUT2A
OUT2B
SENSE2
0.1 μF
X7R
100 μF
3987DS, Rev.1
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