background image
The SLA7024M, SLA7026M, and SMA7029M are designed for
high-efficiency and high-performance operation of 2-phase, unipolar
stepper motors. An automated, innovative packaging technology
combined with power FETs and monolithic logic/control circuitry ad-
vances power multi-chip modules (PMCMs™) toward the complete
integration of motion control. Highly automated manufacturing tech-
niques provide low-cost and exceptionally reliable PMCMs suitable for
controlling and directly driving a broad range of 2-phase, unipolar
stepper motors. The three stepper motor multi-chip modules differ
primarily in output current ratings (1.5 A or 3.0 A) and package style.
All three PMCMs are rated for an absolute maximum limit of 46 V
and utilize advanced NMOS FETs for the high-current, high-voltage
driver outputs. The avalanche-rated (
≥
100 V) FETs provide excellent
ON resistance, improved body diodes, and very-fast switching. The
multi-chip ratings and performance afford significant benefits and
advantages for stepper drives when compared to the higher dissipation
and slower switching speeds associated with bipolar transistors.
Normally, heat sinks are not required for the SLA7024M or SMA7029M.
The SLA7026M, in demanding, higher-current systems designs,
necessitates suitable heat transfer methods for reliable operation.
Complete applications information is given on the following pages.
PWM current is regulated by appropriately choosing current-sensing
resistors, a voltage reference, a voltage divider, and RC timing net-
works. The RC components limit the OFF interval and control current
decay. Inputs are compatible with 5 V logic and microprocessors.
BENEFITS AND FEATURES
s
Cost-Effective, Multi-Chip Solution
s
‘Turn-Key’ Motion-Control Module
s
Motor Operation to 3 A and 46 V
s
3
rd
Generation High-Voltage FETs
s
100 V, Avalanche-Rated NMOS
s
Low r
DS(on)
NMOS Outputs
s
Advanced, Improved Body Diodes
s
Single-Supply Motor/Module
Operation
SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
Data Sheet
28201
Always order by complete part number:
Part Number
Package
Output Current
SLA7024M
18-Lead Power-Tab SIP
1.5 A
SLA7026M
18-Lead Power-Tab SIP
3.0 A
SMA7029M
15-Lead SIP
1.5 A
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
°
C
Load Supply Voltage, V
BB
. . . . . . . . . . . . 46 V
FET Output Voltage, V
DS
. . . . . . . . . . . 100 V
Control Supply Voltage, V
CC
. . . . . . . . . . 46 V
Peak Output Current, I
OUTM
(t
w
≤
100
µ
s)
SLA7024M . . . . . . . . . . . . . . . . . . . . . 3.0 A
SLA7026M . . . . . . . . . . . . . . . . . . . . . 5.0 A
SMA7029M . . . . . . . . . . . . . . . . . . . . 3.0 A
Continuous Output Current, I
OUT
SLA7024M . . . . . . . . . . . . . . . . . . . . . 1.5 A
SLA7026M . . . . . . . . . . . . . . . . . . . . . 3.0 A
SMA7029M . . . . . . . . . . . . . . . . . . . . 1.5 A
Input Voltage Range, V
IN
. . . . -0.3 V to 7.0 V
Reference Voltage, V
REF
. . . . . . . . . . . 2.0 V
Package Power Dissipation, P
D
.
See Graph
Junction Temperature, T
J
. . . . . . . . . +150
°
C
Operating Temperature Range,
T
A
. . . . . . . . . . . . . . . . . . . . -20
°
C to +85
°
C
Storage Temperature Range,
T
stg
. . . . . . . . . . . . . . . . . . -40
°
C to +150
°
C
s
Half- or Full-Step Unipolar Drive
s
High-Efficiency, High-Speed PWM
s
Dual PWM Current Control (2-Phase)
s
Programmable PWM Current Control
s
Low Component Count PWM Drive
s
Low Internal Power Dissipation
s
Heat Sinking (Normally) Unnecessary
s
Electrically Isolated Power Tab
s
Logic IC- and
µ
P-Compatible Inputs
s
Machine-Insertable Package
REFERENCE A
V
REF
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Dwg. PK-007
OUT A
OUTB
SENSEA
GROUND A
V
REF
V
CC
+
+
OUTA
CONTROL/LOGIC
OUTB
GROUND B
REFERENCE B
CNTRL SPLY
IN A
IN B
SENSE B
OFF DELAYA
OFF DELAY B
CONTROL/LOGIC
™
SLA7024M, SLA7026M,
AND
SMA7029M
background image
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
SLA7024M and SLA7026M FUNCTIONAL BLOCK DIAGRAM
Note that channels A and B are electrically isolated.
SMA7029M FUNCTIONAL BLOCK DIAGRAM
Note that except for the control supply, channels A and B are electrically isolated.
+
13
Dwg. FK-005-1
+
8
12
9
15
10
14
11
REG.
8
5
3
2
4
6
7
1
VCC
SENSE
GROUND
OFF-TIME
DELAY
CONTROL
SUPPLY
IN A/B
OUTA/B
OUT A/B
REFERENCE
CHANNEL A PIN NUMBERS
CHANNEL B PIN NUMBERS
+
14
Dwg. FK-005
+
12
15
10
11
18
16
17
13
REG.
7
6
5
3
2
4
1
9
8
V
CC
IN
A/B
SENSE
GROUND
OFF-TIME
DELAY
CONTROL
SUPPLY
IN
A/B
OUT
A/B
OUT
A/B
REFERENCE
CHANNEL A PIN NUMBERS
CHANNEL B PIN NUMBERS
Copyright © 1994 Allegro MicroSystems, Inc.
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ALLOWABLE PACKAGE
POWER DISSIPATION
SLA7024M and SLA7026M
ELECTRICAL CHARACTERISTICS at T
A
= +25
°
C
Limits
Characteristic
Symbol
Test Conditions
Min
Typ
Max
Units
FET Leakage Current
I
DSS
V
DS
= 100 V, V
CC
= 44 V
—
—
4.0
mA
FET ON Voltage
V
DS(ON)
(SLA7024M & SMA7029M) V
CC
= 14 V, I
OUT
= 1 A
—
—
600
mV
(SLA7026M) V
CC
= 14 V, I
OUT
= 3 A
—
—
850
mV
FET ON Resistance
r
DS(on)
(SLA7024M & SMA7029M) V
CC
= 14 V, I
OUT
= 1 A
—
—
600
m
Ω
(SLA7026M) V
CC
= 14 V, I
OUT
= 3 A
—
—
285
m
Ω
Body Diode
V
SD
(SLA7024M & SMA7029M) I
OUT
= –1 A
—
0.9
1.5
V
Forward Voltage
(SLA7026M) I
OUT
= –3 A
—
0.9
1.6
V
Control Supply Voltage
V
CC
Operating
10
24
44
V
Control Supply Current
I
CC
V
CC
= 44 V
—
10
15
mA
Input Current
I
IN(H)
V
CC
= 44 V, V
IN
= 2.4 V
—
—
40
µ
A
I
IN(L)
V
IN
= 0.4 V
—
—
-800
µ
A
Input Voltage
V
IN(H)
2.0
—
—
V
V
IN(L)
—
—
0.8
V
NOTE: Negative current is defined as coming out of (sourcing) the specified device pin.
50
75
100
125
150
25
15
10
5
0
TEMPERATURE in
°
C
20
25
Dwg. GK-018
ALLOWABLE PACKAGE POWER DISSIPATION in WATTS
PREFIX 'SLA'
R = 5.0
°
C/W
θ
JM
PREFIX 'SMA'
R = 31
°
C/W
θ
JA
PREFIX 'SMA'
R = 6.0
°
C/W
θ
JM
PREFIX 'SLA'
R = 28
°
C/W
θ
JA
REFERENCE
A
V
REF
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Dwg. PK-006
OUT
A
OUT
B
SENSE
A
GROUND
A
CNTRL SPLY
A
V
REF
V
CC
+
+
OUT
A
CONTROL/LOGIC
OUT
B
GROUND
B
REFERENCE
B
CNTRL SPLY
B
IN
A
IN
A
IN
B
IN
B
SENSE
B
OFF DELAY
A
OFF DELAY
B
CONTROL/LOGIC
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
background image
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
2.4 k
Ω
R
+
14
Dwg. EK-008
+
12
15
10
18
16
17
13
REG.
V
CC
V
BB
A
B
OUT
A
IN B
IN B
11
B
OUT
V +5 V
+5 V
R 510
Ω
R 100
Ω
47 k
Ω
R
470 pF
C
C 2200 pF
R
≤
1
Ω
S
TO
CHANNEL
A
V
REF
SENSE
t d
3
b
1
2
5
3
1
TYPICAL STEPPER MOTOR APPLICATIONS
(Half of Each Device Shown)
SLA7024M and SLA7026M
TRUTH TABLES
(Device Types as Designated)
WAVE DRIVE (FULL STEP)
for SLA7024M and SLA7026M
Sequence
0
1
2
3
0
Input A
H
L
L
L
H
Input A
L
L
H
L
L
Input B
L
H
L
L
L
Input B
L
L
L
H
L
Output ON
A
B
A
B
A
HALF-STEP OPERATION (2-1-2 SEQUENCE)
for SLA7024M, SLA7026M, and SMA7029M
Sequence
0
1
2
3
4
5
6
7
0
Input A
H
H
L
L
L
L
L
H
H
Input A or t
dA
*
L
L
L
H
H
H
L
L
L
Input B
L
H
H
H
L
L
L
L
L
Input B or t
dB
*
L
L
L
L
L
H
H
H
L
Output(s) ON
A
AB
B
A B
A
AB
B
A B
A
*Logic signals to external open-collector inverter connected to t
dA
and t
dB
.
2-PHASE (FULL STEP) OPERATION
for SLA7024M and SLA7026M
Sequence
0
1
2
3
0
Input A
H
L
L
H
H
Input A
L
H
H
L
L
Input B
H
H
L
L
H
Input B
L
L
H
H
L
Outputs ON
AB
A B
AB
A B
AB
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2.4 k
Ω
R
+
13
Dwg. EK-008-1
+
8
12
9
10
14
11
REG.
V
CC
V
BB
A
B
OUT
A
IN B
15
B
OUT
V +5 V
+5 V
R 510
Ω
R 100
Ω
R 47 k
Ω
C
470 pF
C 2200 pF
R
≤
1
Ω
S
TO
CHANNEL
A
V
REF
SENSE
t d
3
b
1
2
5
1
3
OPEN-COLLECTOR
INVERTER
WAVE DRIVE (FULL STEP) for SMA7029M
Sequence
0
1
2
3
0
Input A
H
L
L
L
H
Input tdA*
L
L
H
L
L
Input B
L
H
L
L
L
Input tdB*
L
L
L
H
L
Output ON
A
B
A
B
A
*Logic signals to external open-collector inverter connected to t
dA
and t
dB
.
TRUTH TABLES
(SMA7029M Only)
TYPICAL STEPPER MOTOR APPLICATIONS
(Half of Device Shown)
SMA7029M
2- PHASE (FULL STEP) OPERATION
for SMA7029M
Sequence
0
1
2
3
0
Input A
H
H
L
L
H
Input B
L
H
H
L
L
Outputs ON
A B
AB
A B
AB
A B
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
background image
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
FIGURE 2. PWM CONTROL (RUN MODE)
Dwg. EK-009
V
INPUT
PEAK
CURRENT
DETECTOR
CONTROL
LOGIC
S
V
BB
V
CC
CURRENT
CONTROL
&
RECIRCULATING
CURRENT
CONTROL
R 2
R 1
R
A
A
B
B
R 5
C 3
R 3
C 1
REF
V
t d
PWM
OFF-TIME
CONTROL
SENSE
b
APPLICATIONS INFORMATION
REGULATING THE PWM OUTPUT CURRENT
The output current (and motor coil current) waveform is illustrated in
Figure 1. Setting the PWM current trip point requires various external
components:
V
b
= Reference supply (typically 5 V)
R
1
, R
2
= Voltage-divider resistors in the reference supply circuit
R
S
= Current sensing resistor(s)
NOTE: The maximum allowable V
REF
input voltage is 2.0 V.
The voltage-divider must be selected accordingly.
Normal PWM (Full-Current/Running) Mode
I
OUT
is set to meet the specified running current for the motor (Figure 2)
and is determined by:
I
OUT
≈
V
REF
(1)
R
S
or, if V
REF
is not known
I
OUT
≈
R
2
•
V
b
(2)
R
1
+ R
2
R
S
FIGURE 1. PHASE A COIL CURRENT WAVEFORM
Dwg. WK-001
PHASE A
PHASE A
0
I
OUT
background image
For given values of R
1
, R
2
, and V
b
(V
REF
≈
0.82 V), Figure 3 illustrates
output current as a function of current-sensing resistance (R
S
).
Reduced/Holding Current Mode
Additional circuitry (Figure 4) enables reducing motor current. The
external transistor changes the voltage-divider ratio, V
REF
, and reduces the
output current. I
HOLD
is determined by resistors R
2
and R
X
in parallel:
I
HOLD
≈
R
2
R
X
•
V
b
(3)
R
1
R
2
+ R
1
R
X
+ R
2
R
X
R
S
or
I
HOLD
≈
R
2
’
•
V
b
(4)
R
1
+ R
2
’
R
S
where R
2
’
= the equivalent value of R
2
and R
X
in parallel.
FIGURE 4. HOLD CURRENT MODE
FIGURE 3. CURRENT-SENSING RESISTANCE
3.0
2.0
1.0
0
1.5
2.5
3.5
0.5
CURRENT-SENSING RESISTANCE in OHMS
OUTPUT TRIP CURRENT in AMPERES
Dwg. GK-014
1.5
2.5
0
0.5
1.0
2.0
3.0
4.0
R
1
= 510
Ω
R
2
= 100
Ω
V
b
= 5 V
R
X
=
∞
SLA7024M & SMA7029M MAX.
SLA7026M MAX.
Dwg. EK-010
RS
V
REF
SENSE
R 1
R 2
HOLD
R 5
C 3
R X
V b
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
background image
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
For given values of R
1
, R
2
, and V
b
(V
REF
≈
0.82 V), Figures 5A and 5B
illustrate output holding current as a function of R
X
for two values of current-
sensing resistance (R
S
).
1.0
0.6
0
0
300
500
HOLDING-CURRENT RESISTANCE in OHMS
OUTPUT TRIP CURRENT in AMPERES
Dwg. GK-015
100
200
400
600
R
1
= 510
Ω
R
2
= 100
Ω
V
b
= 5 V
R
S
= 0.8
Ω
R
S
= 1.0
Ω
0.8
0.4
0.2
FIGURE 5A. HOLD-CURRENT RESISTANCE
(SLA7024M and SMA7029M)
NOTE: Holding current determines holding torque, which is normally
greater than running torque. Consult motor manufacturer for recommended
safe holding current and motor winding temperature limits in “standstill” or
“detent” mode.
FIGURE 5B. HOLD-CURRENT RESISTANCE (SLA7026M)
The MOSFET outputs create ringing noise with PWM, but the RC filter
precludes malfunctions. The comparator operation is affected by R
5
and C
3
and, thus, current overshoot is inf