A3982
DMOS Stepper Motor Driver with Translator
Package LB
OUT2A
SENSE2
VBB2
OUT2B
ENABLE
PGND
PGND
CP1
CP2
1
2
3
4
5
24 OUT1A
23 SENSE1
22 VBB1
21 OUT1B
20 DIR
The A3982 is a complete stepper motor driver with built-in translator
for easy operation. It is designed to operate bipolar stepper motors in
full- and half-step modes, with an output drive capacity of up to 35 V
and ±2 A. The A3982 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 A3982.
Simply inputting one pulse on the STEP input drives the motor one
step. There are no phase sequence tables, high frequency control lines,
or complex interfaces to program. The A3982 interface is an ideal fit
for applications where a complex microprocessor is unavailable or is
overburdened.
The chopping control in the A3982 automatically selects the current
decay mode (Slow or Mixed). When a signal occurs at the STEP input
pin, the A3982 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 current decay is set to Mixed (set initially to a fast
decay for a period amounting to 31.25% of the fixed off-time, then
to a slow decay for the remainder of the off-time). This current decay
control scheme results in 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.
Internal circuit protection includes: thermal shutdown with hysteresis,
undervoltage lockout (UVLO), and crossover-current protection.
Special power-on sequencing is not required.
The A3982 is supplied in a 24-pin wide-body SOIC (package
LB)
with
internally-fused power ground leads. It is also available in a lead (Pb)
free version (suffix
–T),
with 100% matte tin plated leadframes.
Translator
& Control Logic
6
7
8
19 PGND
18 PGND
17 REF
16 STEP
15 VDD
9
VCP 10
VREG 11
MS1 12
Charge
Pump
OSC
Reg
14 ROSC
13 RESET
Approximate Scale 1:1
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage,V
BB
...................................35
V
Output Current, I
OUT
.........................................
±2 A
*
Logic Input Voltage, V
IN
.....................
–0.3 V to 7 V
Sense Voltage, V
SENSE
.......................................0.5
V
Reference Voltage, V
REF
………..........................4
V
Operating Temperature Range
Ambient, T
A
.................................
–20°C to 85°C
Junction Temperature, T
J(MAX)
.....................
150°C
Storage Temperature, T
S
....................
–55°C to 150°C
FEATURES
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 and thermal shutdown circuitry
Crossover-current protection
Pb-free
–
Yes
Package
24-pin, Wide SOIC
*
Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any
set of conditions, do not exceed the specified current
rating or a junction temperature of 150°C.
Use the following complete part number when ordering:
Part Number
A3982SLB
A3982SLB-T
Ambient
–20°C to 85°C
26184.28B
A3982
DMOS Stepper Motor Driver with Translator
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
Motor Supply Current
Logic Supply Current
Control Logic
Logic Input Voltage
Logic Input Current
Input Hysteresis
Blank Time
Fixed Off-Time
Reference Input Voltage Range
Reference Input Current
Current Trip-Level Error
3
Crossover Dead Time
Protection
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
UVLO Enable Threshold
UVLO Hysteresis
V
IN(1)
V
IN(0)
I
IN(1)
I
IN(0)
V
HYS(IN)
t
BLANK
t
OFF
V
REF
I
REF
err
I
Symbol
V
BB
V
DD
R
DSON
V
F
I
BB
I
DD
Test Conditions
Operating
Operating
Source Driver, I
OUT
= –1.5 A
Sink Driver, I
OUT
= 1.5 A
Source Diode, I
F
= –1.5 A
Sink Diode, I
F
= 1.5 A
f
PWM
< 50 kHz
Operating, outputs disabled
f
PWM
< 50 kHz
Outputs off
Min.
8
3.0
–
–
–
–
–
–
–
–
V
DD
×
0.7
Typ.
2
–
–
0.370
0.330
–
–
–
–
–
–
–
–
<1.0
<1.0
300
1
30
30
–
0
–
–
475
165
15
2.7
0.10
Max.
35
5.5
0.460
0.380
1.2
1.2
4
2
8
5
–
V
DD
×
0.3
20
20
500
1.3
40
37
4
3
±5
±5
800
–
–
3
–
Units
V
V
Ω
Ω
V
V
mA
mA
mA
mA
V
V
μA
μA
mV
μs
μs
μs
V
μA
%
%
ns
°C
°C
V
V
V
IN
= V
DD
×
0.7
–
–20
–20
150
0.7
20
23
0
–3
–
–
100
–
–
2.35
0.05
V
IN
= V
DD
×
0.3
OSC > 3 V
R
OSC
= 25 kΩ
V
REF
= 2 V,
%I
TripMAX
= 70.71%
V
REF
= 2 V,
%I
TripMAX
= 100.00%
t
DT
T
J
T
JHYS
UV
LO
UV
HYS
V
DD
rising
1
Negative current is defined as coming out of (sourcing from) the specified device pin.
2
Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions. Performance may vary for
3
err
individual units, within the specified maximum and minimum limits.
I
= (I
Trip
– I
Prog
)
⁄
I
Prog
, where I
Prog
= %I
TripMAX
I
TripMAX
.
×
26184.28B
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A3982
DMOS Stepper Motor Driver with Translator
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions*
One-layer PCB, one-sided with copper limited to solder pads
Package Thermal Resistance
R
θJA
One layer PCB, two-sided with copper limited to solder pads and
3.57 in.
2
of copper area on each side, connected to PGND pins
High-K PCB (multilayer with significant copper areas, based on
JEDEC standard)
Value Units
77
45
35
ºC/W
ºC/W
ºC/W
*In still air. Additional thermal information available on Allegro Web site.
Power Dissipation versus Ambient Temperature
4.00
3.50
Power Dissipation, P
D
(W)
3.00
2.50
2.00
1.50
1.00
0.50
0
R
θ
J
A
=
35
45
R
ºC
θ
J
/W
/W
A
=
ºC
R
θ
JA
=7
7 ºC
/W
20
40
60
80
100
120
Temperature, T
A
(°C)
140
160
26184.28B
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A3982
DMOS Stepper Motor Driver with Translator
t
A
t
B
STEP
t
C
MS1,
RESET, or DIR
t
D
Time Duration
STEP minimum, HIGH pulse width
STEP minimum, LOW pulse width
Setup time, input change to STEP
Hold time, input change to STEP
Figure 1. Logic Interface Timing Diagram
Symbol
t
A
t
B
t
C
t
D
Typ.
1
1
200
200
Unit
μs
μs
ns
ns
Table 1. Stepping Resolution Truth Table
MS1
L
H
Step Resolution
Full Step
Half Step
Excitation Mode
2 Phase
1-2 Phase
26184.28B
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
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