A4987
DMOS Dual Full-Bridge PWM Motor Driver
With Overcurrent Protection
Features and Benefits
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Low R
DS(ON)
outputs
Internal mixed current decay mode
Synchronous rectification for low power dissipation
Internal UVLO
Crossover-current protection
3.3 and 5 V compatible logic supply
Thin profile QFN and TSSOP packages
Thermal shutdown circuitry
Short-to-ground protection
Shorted load protection
Low current Sleep mode, < 10
μA
Description
The A4987 is a dual DMOS full-bridge stepper motor driver
with parallel input communication and overcurrent protection.
Each full-bridge output is rated up to 35 V and ±1 A. The A4987
includes fixed off-time pulse width modulation (PWM) current
regulators, along with 2- bit nonlinear DACs (digital-to-analog
converters) that allow stepper motors to be controlled in full,
half, and quarter steps. The PWM current regulator uses the
Allegro
™
patented mixed decay mode for 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.
The outputs are protected from shorted load and short-to-
ground events, which protect the driver and associated circuitry
from thermal damage or flare-ups. Other protection features
include thermal shutdown with hysteresis, undervoltage lockout
(UVLO) and crossover current protection. Special power-up
sequencing is not required.
The A4987 is supplied in two packages, a 24-contact QFN (ES)
and a 24-pin TSSOP (LP). Both packages have exposed thermal
pads for enhanced thermal performance. The 24-contact ES is
4 mm × 4 mm, with a nominal overall package height of 0.75
mm. The 24-pin LP is a TSSOP with 0.65 pitch and an overall
package height of
≤1.2
mm. Both packages are lead (Pb) free,
with 100% matte tin leadframe plating.
Packages
:
24-contact QFN
4 mm × 4 mm × 0.75 mm
(ES package)
Approximate size
24-pin TSSOP
with exposed thermal pad
(LP Package)
Typical Application Diagram
V
DD
0.22
μF
VREG ROSC
VDD
CP1
CP2
VCP
0.1
μF
0.1
μF
0.22
μF
VBB1
VBB2
OUT1A
100
μF
Microcontroller or
Controller Logic
SLEEP
IN01
IN02
PH1
IN11
IN12
PH2
VREF
A4987
OUT1B
SENSE1
OUT2A
OUT2B
GND
GND
SENSE2
4987-DS, Rev. 5
A4987
DMOS Dual Full-Bridge PWM Motor Driver
With Overcurrent Protection
Selection Guide
Part Number
A4987SESTR-T
A4987SLPTR-T
Package
24-pin QFN with exposed thermal pad
24-pin TSSOP with exposed thermal pad
Packing
1500 pieces per 7-in. reel
4000 pieces per 13-in. reel
Absolute Maximum Ratings
Characteristic
Load Supply Voltage
Output Current
Logic Input Voltage
Logic Supply Voltage
Motor Outputs Voltage
Sense Voltage
Reference Voltage
Operating Ambient Temperature
Maximum Junction
Storage Temperature
V
SENSE
V
REF
T
A
T
J
(max)
T
stg
Range S
Symbol
V
BB
I
OUT
V
IN
V
DD
Notes
Rating
35
±1
–0.3 to 5.5
–0.3 to 5.5
–2.0 to 37
–0.5 to 0.5
5.5
–20 to 85
150
–55 to 150
Units
V
A
V
V
V
V
V
ºC
ºC
ºC
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
A4987
DMOS Dual Full-Bridge PWM Motor Driver
With Overcurrent Protection
Functional Block Diagram
0.1
μF
Rosc
VREG
0.22
μF
REGULATOR
OSC
CHARGE PUMP
VCP
CP1
CP2
0.1
μF
DMOS FULL-BRIDGE 1
VBB1
Sense2
To
V
BB2
-
DAC
OSC
OCP
+
OUT1A
PWM Latch
BLANKING
Mixed Decay
V
REF
OUT1B
VDD
IN01
IN02
PH1
IN11
IN12
PH2
SLEEP
CONTROL
LOGIC
GATE
DRIVE
SENSE1
DMOS FULL-BRIDGE 2
VBB2
OCP
OUT2A
PWM Latch
BLANKING
Mixed Decay
OSC
V
CP
V
REG
V
REG
OUT2B
REF
V
REF
Sense2
Sense2
GND
GND
SENSE2
-
+
V
REF
DAC
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A4987
DMOS Dual Full-Bridge PWM Motor Driver
With Overcurrent Protection
Symbol
Test Conditions
Operating
During Sleep Mode
Operating
Source Driver, I
OUT
= –800 mA
Sink Driver, I
OUT
= 800 mA
Source Diode, I
F
= –800 mA
Sink Diode, I
F
= 800 mA
f
PWM
< 50 kHz
Operating, outputs disabled
Sleep Mode
f
PWM
< 50 kHz
Outputs off
Sleep Mode
Min.
8
0
3.0
–
–
–
–
–
–
–
–
–
–
V
DD
0.7
V
IN
= V
DD
0.7
–
–20
–20
–
–
5
0.7
20
23
0
–3
–
–
–
100
1.1
–
–
2.7
–
Typ.
2
–
–
–
700
700
–
–
–
–
–
–
–
–
–
–
<1.0
<1.0
100
50
11
1
30
30
–
0
–
–
–
475
–
165
15
2.8
90
Max.
35
35
5.5
900
900
1.3
1.3
4
2
10
8
5
10
–
V
DD
0.3
20
20
–
–
19
1.3
40
37
4
3
±15
±5
±5
800
–
–
–
2.9
–
Units
V
V
V
mΩ
mΩ
V
V
mA
mA
μA
mA
mA
μA
V
V
μA
μA
kΩ
kΩ
%
μs
μs
μs
V
μA
%
%
%
ns
A
°C
°C
V
mV
ELECTRICAL CHARACTERISTICS
1
at T
A
= 25°C, V
BB
= 35 V (unless otherwise noted)
Characteristics
Output Drivers
Load Supply Voltage Range
Logic Supply Voltage Range
Output On Resistance
Body Diode Forward Voltage
V
BB
V
DD
R
DS(ON)
V
F
I
BB
Motor Supply Current
Logic Supply Current
Control Logic
Logic Input Voltage
Logic Input Current
Logic Input Pull-down
Logic Input Hysteresis
Blank Time
Fixed Off-Time
Reference Input Voltage Range
Reference Input Current
Current Trip-Level Error
3
Crossover Dead Time
Protection
Overcurrent Protection Threshold
4
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
VDD Undervoltage Lockout
VDD Undervoltage Hysteresis
1
For
2
Typical
I
DD
V
IN(1)
V
IN(0)
I
IN(1)
I
IN(0)
R
IN02
R
IN12
V
HYS(IN)
t
BLANK
t
OFF
V
REF
I
REF
err
I
V
IN
= V
DD
0.3
As a % of V
DD
OSC = VDD or GND
R
OSC
= 25 kΩ
V
REF
= 2 V,
%I
TripMAX
=
33.3%
V
REF
= 2 V,
%I
TripMAX
= 66.7%
V
REF
= 2 V,
%I
TripMAX
= 100.00%
t
DT
I
OCPST
T
TSD
T
TSDHYS
V
DDUVLO
V
DDUVLOHYS
V
DD
rising
input and output current specifications, negative current is defined as coming out of (sourcing) the specified device pin.
data are for initial design estimations only, and assume optimum manufacturing and application conditions. Performance may vary for individual
units, within the specified maximum and minimum limits.
3
V
ERR
= [(V
REF
/8) – V
SENSE
] / (V
REF
/8).
4
Overcurrent protection (OCP) is tested at T = 25°C in a restricted range and guaranteed by characterization.
A
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A4987
DMOS Dual Full-Bridge PWM Motor Driver
With Overcurrent Protection
THERMAL CHARACTERISTICS may require derating at maximum conditions
Characteristic
Package Thermal Resistance
Symbol
R
θJA
Test Conditions*
ES package; estimated, on 4-layer PCB, based on JEDEC standard
LP package; on 4-layer PCB, based on JEDEC standard
Value Units
37
28
ºC/W
ºC/W
*In still air. Additional thermal information available on Allegro Web site.
Maximum Power Dissipation, P
D
(max)
5.5
5.0
4.5
4.0
Power Dissipation, P
D
(W)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
(R
θ
J
A
(R
θ
J
A
=
28
ºC
/W
=3
)
7º
C/
W
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
