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Número de pieza | A4988 | |
Descripción | DMOS Microstepping Driver | |
Fabricantes | Allegro | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de A4988 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
No Preview Available ! A4988
DMOS Microstepping Driver with Translator
and Overcurrent Protection
Features and Benefits
▪ 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
Package:
28-contact QFN
with exposed thermal pad
5 mm × 5 mm × 0.90 mm
(ET package)
Not to scale
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.
Continued on the next page…
Microcontroller or
Controller Logic
Typical Application Diagram
VDD
0.22 µF
0.1 µF
0.1 µF
0.22 µF
5 kΩ
VREG ROSC CP1 CP2 VCP VBB1
VDD
VBB2
SLEEP
STEP
MS1
MS2
MS3
DIR
ENABLE
RESET
VREF
A4988
OUT1A
OUT1B
SENSE1
GND
OUT2A
OUT2B
SENSE2
GND
4988-DS, Rev. 6
100 µF
1 page A4988
DMOS Microstepping Driver with Translator
and Overcurrent Protection
THERMAL CHARACTERISTICS
Characteristic
Package Thermal Resistance
Symbol
Test Conditions*
RθJA Four-layer PCB, based on JEDEC standard
*Additional thermal information available on Allegro website.
Value Units
32 ºC/W
Power Dissipation versus Ambient Temperature
4.00
3.50
3.00
2.50
2.00
1.50
R
θJA = 32 ºC/W
1.00
0.50
0
20 40 60 80 100 120 140 160
Temperature, TA (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
5 Page A4988
VSTEP
100.00
70.71
IOUT
0
DMOS Microstepping Driver with Translator
and Overcurrent Protection
See Enlargement A
–70.71
–100.00
IOUT
Enlargement A
IPEAK
tFD
toff
tSD
Slow Decay
Mixed Decay
Fast Decay
Symbol
toff
IPEAK
tSD
tFD
IOUT
Device fixed off-time
Maximum output current
Slow decay interval
Fast decay interval
Device output current
Characteristic
t
Figure 7: Current Decay Modes Timing Chart
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
11 Page |
Páginas | Total 20 Páginas | |
PDF Descargar | [ Datasheet A4988.PDF ] |
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