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PDF A3989 Data sheet ( Hoja de datos )
| Número de pieza | A3989 | |
| Descripción | Bipolar Stepper and High Current DC Motor Driver | |
| Fabricantes | Allegro MicroSystems | |
| Logotipo |  |
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A3989
Bipolar Stepper and High Current DC Motor Driver
Features and Benefits
▪ 36 V output rating
▪ 2.4 A dc motor driver
▪ 1.2 A bipolar stepper driver
▪ Synchronous rectification
▪ Internal undervoltage lockout (UVLO)
▪ Thermal shutdown circuitry
▪ Crossover-current protection
▪ Very thin profile QFN package
Description
The A3989 is designed operate at voltages up to 36 V while driving
one bipolar stepper motor, at currents up to 1.2A, and one dc motor,
at currents up to 2.4 A. The A3989 includes a fixed off-time pulse
width modulation (PWM) regulator for current control. The stepper
motor driver features dual 2-bit nonlinear DACs (digital-to-analog
converters) that enable control in full, half, and quarter steps. The
dc motor is controlled using standard PHASE and ENABLE signals.
Fast or slow current decay is selected via the MODE pin. The PWM
current regulator uses the Allegro® patented mixed decay mode for
reduced audible motor noise, increased step accuracy, and reduced
power dissipation.
Package: 36 pin QFN with exposed thermal pad
0.90 mm nominal height (suffix EV)
Internal synchronous rectification control circuitry is provided to
improve power dissipation during PWM operation.
Protection features include thermal shutdown with hysteresis,
undervoltage lockout (UVLO) and crossover current protection.
Special power up sequencing is not required.
The A3989 is supplied in a leadless 6 mm × 6 mm × 0.9 mm,
36 pin QFN package with exposed power tab for enhanced thermal
www.DataSheetp4Ue.crofmormance. The package is lead (Pb) free, with 100% matte tin
leadframe plating.
Approximate scale 1:1
Microcontroller or
Controller Logic
A3989DS
0.1 µF
50 V
CP1
VDD
0.1 µF
50 V
CP2 VCP
100 µF
50 V
VBB VBB
OUT1A
PHASE1
I01
A3989
I11
PHASE2
I02
I12
PHASE3
ENABLE
MODE
VREF1
VREF2
VREF3
GND GND
OUT1B
SENSE1
OUT2A
OUT2B
SENSE2
OUT3A
OUT3A
OUT3B
OUT3B
SENSE3
SENSE3
Figure 1. Typical application circuit
0.22 µF
50 V
1 page  
A3989
Bipolar Stepper and High Current DC Motor Driver
Functional Description
Device Operation The A3989 is designed to operate one
dc motor and one bipolar stepper motor. The currents in each of
the full bridges, all N-channel DMOS, are regulated with fixed
off-time pulse width modulated (PWM) control circuitry. The
peak current in each full bridge is set by the value of an external
current sense resistor, RSx , and a reference voltage, VREFx .
If the logic inputs are pulled up to VDD, it is good practice to use
a high value pullup resistor in order to limit current to the logic
inputs should an overvoltage event occur. Logic inputs include:
PHASEx, I0x, I1x, ENABLE, and MODE.
Internal PWM Current Control Each full-bridge is
controlled by a fixed off-time PWM current control circuit that
limits the load current to a user-specified value, ITRIP . Initially,
a diagonal pair of source and sink DMOS outputs are enabled
and current flows through the motor winding and RSx. When the
voltage across the current sense resistor equals the voltage on the
VREFx pin, the current sense comparator resets the PWM latch,
which turns off the source driver.
The maximum value of current limiting is set by the selection of
RS and the voltage at the VREF input with a transconductance
function approximated by:
ITripMax = VREF / (3×RS)
The stepper motor outputs will define each current step as a
percentage of the maximum current, ITripMax. The actual current at
each step ITrip is approximated by:
ITrip = (% ITripMax / 100) ITripMax
where % ITripMax is given in the Step Sequencing table.
Note: It is critical to ensure that the maximum rating of ±500 mV
on each SENSEx pin is not exceeded.
Fixed Off-Time The internal PWM current control circuitry
uses a one shot circuit to control the time the drivers remain off.
The one shot off-time, toff , is internally set to 30 µs.
Blanking This function blanks the output of the current sense
comparator when the outputs are switched by the internal current
control circuitry. The comparator output is blanked to prevent
false detections of overcurrent conditions, due to reverse recovery
currents of the clamp diodes, or to switching transients related to
the capacitance of the load. Dc motors require more blank time
than stepper motors. The stepper driver blank time, tBLANKst ,
is approximately 1 μs. The dc driver blank time, tBLANKdc , is
approximately 3 μs.
Control Logic Stepper motor communication is implemented
via industry standard I1, I0, and PHASE interface. This commu-
nication logic allows for full, half, and quarter step modes. Each
bridge also has an independent VREF input so higher resolution step
modes can be programmed by dynamically changing the voltage
on the corresponding VREFx pin. The dc motor is controlled using
standard PHASE, ENABLE communication. Fast or slow current
decay during the off-time is selected via the MODE pin.
Charge Pump (CP1 and CP2) The charge pump is used to
generate a gate supply greater than the VBB in order to drive the
source-side DMOS gates. A 0.1 μF ceramic capacitor should be
connected between CP1 and CP2 for pumping purposes. A 0.1 μF
ceramic capacitor is required between VCP and VBBx to act as a
reservoir to operate the high-side DMOS devices.
Shutdown In the event of a fault (excessive junction tem-
perature, or low voltage on VCP), the outputs of the device are
disabled until the fault condition is removed. At power-up, the
undervoltage lockout (UVLO) circuit disables the drivers.
Synchronous Rectification When a PWM-off cycle is
triggered by an internal fixed off-time cycle, load current will
recirculate. The A3989 synchronous rectification feature will
turn on the appropriate MOSFETs during the current decay. This
effectively shorts the body diode with the low RDS(on) driver. This
significantly lowers power dissipation. When a zero current level
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5 Page 
A3989
Bipolar Stepper and High Current DC Motor Driver
Pin-out Diagram
I12 28
I11 29
GND 30
VCP 31
CP1 32
CP2 33
I01 34
I02 35
ENABLE 36
PAD
18 PHASE1
17 PHASE2
16 GND
15 NC
14 VREF3
13 VREF2
12 VREF1
11 VDD
10 PHASE3
Terminal List Table
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Name
NC
OUT1A
SENSE1
OUT1B
VBB
OUT2B
SENSE2
OUT2A
NC
PHASE3
VDD
VREF1
VREF2
VREF3
NC
GND
PHASE2
PHASE1
NC
OUT3A
SENSE3
OUT3B
VBB
OUT3B
SENSE3
OUT3A
MODE
I12
I11
GND
VCP
CP1
CP2
I01
I02
ENABLE
– PAD
Description
No Connect
DMOS Full Bridge 1 Output A
Sense Resistor Terminal for Bridge 1
DMOS Full Bridge 1 Output B
Load Supply Voltage
DMOS Full Bridge 2 Output B
Sense Resistor Terminal for Bridge 2
DMOS Full Bridge 2 Output A
No Connect
Control Input
Logic Supply Voltage
Analog Input
Analog Input
Analog Input
No Connect
Ground
Control Input
Control Input
No Connect
DMOS Full Bridge 3 Output A
Sense Resistor Terminal for Bridge 3
DMOS Full Bridge 3 Output B
Load Supply Voltage
DMOS Full Bridge 3 Output A
Sense Resistor Terminal for Bridge 3
DMOS Full Bridge 3 Output B
Control Input
Control Input
Control Input
Ground
Reservoir Capacitor Terminal
Charge Pump Capacitor Terminal
Charge Pump Capacitor Terminal
Control Input
Control Input
Control Input
Exposed pad for enhanced thermal performance. Should
be soldered to the PCB
Allegro MicroSystems, Inc.
11
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet A3989.PDF ] | |
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