SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
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
■ Cost-Effective, Multi-Chip Solution
■ ‘Turn-Key’ Motion-Control Module
■ Motor Operation to 3 A and 46 V
■ 3
rd
Generation High-Voltage FETs
■ 100 V, Avalanche-Rated NMOS
■ Low r
DS(on)
NMOS Outputs
■ Advanced, Improved Body Diodes
■ Single-Supply Motor/Module
Operation
SMA7029M
SLA7024M, SLA7026M,
AND
SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
Data Sheet
28201
TM
MicroSystems, Inc.
TM
A
A
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 TA = +25°C
Load Supply Voltage, VBB . . . . . . . . . . . . 46 V
FET Output Voltage, VDS . . . . . . . . . . . 100 V
Control Supply Voltage, VCC . . . . . . . . . . 46 V
Peak Output Current, IOUTM (tw ≤ 100 µs)
SLA7024M . . . . . . . . . . . . . . . . . . . . . 3.0 A
SLA7026M . . . . . . . . . . . . . . . . . . . . . 5.0 A
SMA7029M . . . . . . . . . . . . . . . . . . . . 3.0 A
Continuous Output Current, IOUT
SLA7024M . . . . . . . . . . . . . . . . . . . . . 1.5 A
SLA7026M . . . . . . . . . . . . . . . . . . . . . 3.0 A
SMA7029M . . . . . . . . . . . . . . . . . . . . 1.5 A
Input Voltage Range, VIN . . . . -0.3 V to 7.0 V
Reference Voltage, VREF . . . . . . . . . . . 2.0 V
Package Power Dissipation, PD. See Graph
Junction Temperature, TJ. . . . . . . . . +150°C
Operating Temperature Range,
TA. . . . . . . . . . . . . . . . . . . . -20°C to +85°C
Storage Temperature Range,
Tstg . . . . . . . . . . . . . . . . . . -40°C to +150°C
■ Half- or Full-Step Unipolar Drive
■ High-Efficiency, High-Speed PWM
■ Dual PWM Current Control (2-Phase)
■ Programmable PWM Current Control
■ Low Component Count PWM Drive
■ Low Internal Power Dissipation
■ Heat Sinking (Normally) Unnecessary
■ Electrically Isolated Power Tab
■ Logic IC- and µP-Compatible Inputs
■ Machine-Insertable Package
REFERENCEA
V
REF
12345678910 11 12 13 14 15
Dwg. PK-007
OUTA
OUTB
SENSEA
GROUNDA
V
REF
V
CC
+
+
OUTA
CONTROL/LOGIC
OUTB
GROUND B
REFERENCEB
CNTRL SPLY
INA
INB
SENSEB
OFF DELAYA
OFF DELAYB
CONTROL/LOGIC
TM
MicroSystems, Inc.
TM
A
A
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1994 Allegro MicroSystems, Inc.
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
SENSEGROUNDOFF-TIME
DELAY
CONTROL
SUPPLY IN A/B OUTA/B OUTA/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
VCC
IN A/B
SENSEGROUNDOFF-TIME
DELAY
CONTROL
SUPPLY IN A/B OUTA/B OUTA/B
REFERENCE
CHANNEL A PIN NUMBERS
CHANNEL B PIN NUMBERS
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
ALLOWABLE PACKAGE
POWER DISSIPATION
SLA7024M and SLA7026M
ELECTRICAL CHARACTERISTICS at TA = +25°C
Limits
Characteristic Symbol Test Conditions Min Typ Max Units
FET Leakage Current IDSS VDS = 100 V, VCC = 44 V — — 4.0 mA
FET ON Voltage VDS(ON) (SLA7024M & SMA7029M) VCC = 14 V, IOUT = 1 A — — 600 mV
(SLA7026M) VCC = 14 V, IOUT = 3 A — — 850 mV
FET ON Resistance rDS(on) (SLA7024M & SMA7029M) VCC = 14 V, IOUT = 1 A — — 600 mΩ
(SLA7026M) VCC = 14 V, IOUT = 3 A — — 285 mΩ
Body Diode VSD (SLA7024M & SMA7029M) IOUT = –1 A — 0.9 1.5 V
Forward Voltage (SLA7026M) IOUT = –3 A — 0.9 1.6 V
Control Supply Voltage VCC Operating 10 24 44 V
Control Supply Current ICC VCC = 44 V — 10 15 mA
Input Current IIN(H) VCC = 44 V, VIN = 2.4 V — — 40 µA
IIN(L) VIN = 0.4 V — — -800 µA
Input Voltage VIN(H) 2.0 — — V
VIN(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
θJM
PREFIX 'SMA'
R = 31°C/W
θJA
PREFIX 'SMA'
R = 6.0°C/W
θJM
PREFIX 'SLA'
R = 28°C/W
θJA
REFERENCEA
V
REF
V
CC
12345 678910111213 14 15 16 17 18
Dwg. PK-006
OUTA
OUTB
SENSEA
GROUNDA
CNTRL SPLYA
V
REF
V
CC
+
+
OUTA
CONTROL/LOGIC
OUTB
GROUNDB
REFERENCEB
CNTRL SPLY B
INA
INA
INB
INB
SENSEB
OFF DELAYA
OFF DELAYB
CONTROL/LOGIC
TM
MicroSystems, Inc.
TM
A
A
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
2.4 kΩ
R
+
14
Dwg. EK-008
+
12
15
10
18
16
17
13
REG.
VCC
VBB
A
B
OUT
A
IN BIN B
11
B
OUT
V +5 V
+5 V
R 510 Ω
R 100 Ω
47 kΩ
R 470 pF
C
C 2200 pF R
≤1 Ω
S
TO
CHANNEL
A
VREF
SENSE
td
3
b
12
5
31
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 345670
Input A H H L LLLLHH
Input A or tdA*LLLHHHLLL
Input B L H H H LLLLL
Input B or tdB*LLLLLHHHL
Output(s) ON A AB B A B A AB B A B A
*Logic signals to external open-collector inverter connected to tdA and tdB.
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
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
2.4 kΩ
R
+
13
Dwg. EK-008-1
+
8
12
9
10
14
11
REG.
VCC
VBB
A
B
OUT
A
IN B
15
B
OUT
V +5 V
+5 V
R 510 Ω
R 100 Ω
R 47 kΩ
C
470 pF C 2200 pF R
≤1 Ω
S
TO
CHANNEL
A
VREF
SENSE
td
3
b
12
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 tdA and tdB.
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
TM
MicroSystems, Inc.
TM
A
A
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
FIGURE 2.␣ PWM CONTROL (RUN MODE)
Dwg. EK-009
VINPUT
PEAK
CURRENT
DETECTOR
CONTROL
LOGIC
S
VBB
VCC
CURRENT
CONTROL
&
RECIRCULATING
CURRENT
CONTROL
R2
R1
R
AA
B
B
R
5
C
3
R
3
C
1
REF
V
td
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:
Vb = Reference supply (typically 5 V)
R1, R2 = Voltage-divider resistors in the reference supply circuit
RS = Current sensing resistor(s)
NOTE: The maximum allowable VREF input voltage is 2.0 V.
The voltage-divider must be selected accordingly.
Normal PWM (Full-Current/Running) Mode
IOUT is set to meet the specified running current for the motor (Figure 2)
and is determined by:
IOUT ≈VREF (1)
RS
or, if VREF is not known
IOUT ≈R2•Vb(2)
R1 + R2RS
FIGURE 1.␣ PHASE A COIL CURRENT WAVEFORM
Dwg. WK-001
PHASE A
PHASE A
0
IOUT
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
For given values of R1, R2, and Vb (VREF ≈ 0.82 V), Figure 3 illustrates
output current as a function of current-sensing resistance (RS).
Reduced/Holding Current Mode
Additional circuitry (Figure 4) enables reducing motor current. The
external transistor changes the voltage-divider ratio, VREF, and reduces the
output current. IHOLD is determined by resistors R2 and RX in parallel:
IHOLD ≈R2 RX•Vb(3)
R1 R2 + R1 RX + R2 RXRS
or IHOLD ≈R2’•Vb(4)
R1 + R 2’RS
where R2’ = the equivalent value of R2 and RX 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
00.5 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
VREF
SENSE
R1
R2
HOLD
R5
C3
RX
Vb
TM
MicroSystems, Inc.
TM
A
A
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
For given values of R1, R2, and Vb (VREF ≈ 0.82 V), Figures 5A and 5B
illustrate output holding current as a function of RX for two values of current-
sensing resistance (RS).
1.0
0.6
00 300 500
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 R5 and C3
and, thus, current overshoot is influenced by component values. Empirical
adjustment to “fine-tune” the current limit is likely.
3.0
2.0
1.0
0300 500 700
0.5
HOLDING-CURRENT RESISTANCE in OHMS
OUTPUT TRIP CURRENT in AMPERES
Dwg. GK-015-1
1.5
2.5
0100 200 400 600 800
R
1
= 510 Ω
R
2
= 100 Ω
V
b
= 5 V R
S
= 0.33 Ω
R
S
= 0.47 Ω
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
Vb
DETERMINING THE MOTOR PWM FREQUENCY
The modules function asynchronously, with PWM OFF time fixed by R3
and C1 at input td. The OFF time can be calculated as:
tOFF ≈ -R3 • C1 • logn (1 - 2 ) (5)
Recommended circuit constants and tOFF are:
Vb = 5 V
R3 = 47 kΩ
C1 = 470 pF
tOFF = 12 µs
FIGURE 7.␣
PWM FREQUENCY vs MOTOR RESISTANCE
POWER DISSIPATION CALCULATIONS
Excepting high-current applications utilizing the SLA7026M above
approximately 2.0 A at +65°C (with 2-phase operation), the need for heat
sinks is rare. The basic constituents of conduction losses (internal power
dissipation) include:
(a) FET output power dissipation (IOUT2 • rDS(on) or IOUT • VDS(ON)),
(b) FET body diode power dissipation (VSD • IOUT), and
(c) control circuit power dissipation (VCC • ICC).
Device conduction losses are calculated based on the operating mode
(wave drive, half-step, or 2-phase). Assuming a 50% output duty cycle:
Wave Drive = 0.5 (IOUT2 • rDS(on)) + 0.5 (VSD • IOUT) + (VCC • 15 mA)
Half-Step = 0.75 (IOUT2 • rDS(on)) + 0.75 (VSD • IOUT) + (VCC • 15 mA)
2-Phase = (IOUT2 • rDS(on)) + (VSD • IOUT) + (VCC • 15 mA)
40
20
0 6 10 14
10
MOTOR RESISTANCE in OHMS
ON TIME in µs
Dwg. GK-016
30
50
024 8 12
R
S
= 1 Ω
L/R = 1 to 3 ms
CHOPPING FREQUENCY in kHz
20
25
30
35
40
V
CC
= 24 V
V
CC
= 36 V
TM
MicroSystems, Inc.
TM
A
A
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
PACKAGE RATINGS/DERATING FACTORS
Thermal ratings/deratings for the multi-chip module packages vary
slightly. Normally, the SLA7024M and SMA7029M do not need heat
sinking when operated within maximum specified output current (≤1.0 A
with 2-phase drive) unless the design ambient temperature also ex-
ceeds +60°C. Thermal calculations must also consider the temperature
effects on the output FET ON resistance. The applicable thermal
ratings for the PMCM packages are:
SLA7024M and SLA7026M 18-Lead Power-Tab SIP
RΘJA = 28°C/W (no heat sink) or 4.5 W at +25°C and a derating
factor of -36 mW/°C for operation above +25°C. RΘJC = 5°C/W.
SMA7029M 15-Lead SIP
RΘJA = 31°C/W (no heat sink) or 4.0 W at +25°C and a derating
factor of -32 mW/°C for operation above +25°C. RΘJC = 6°C/W.
TEMPERATURE EFFECTS ON FET rDS(on)
Analyzing safe, reliable operation includes a concern for the
relationship of NMOS ON resistance to junction temperature. Device
package power calculations must include the increase in ON resistance
(producing higher output ON voltages) caused by higher operating
junction temperatures. Figure 8 provides a normalized ON resistance
curve, and all thermal calculations should consider increases from the
given +25°C limits, which may be caused by internal heating during
normal operation.
FIGURE 8.␣ NORMALIZED ON RESISTANCE
vs TEMPERATURE
2.0
1.0
-40 +80 +160
0.5
JUNCTION TEMPERATURE in °C
NORMALIZED FET ON RESISTANCE
Dwg. GK-017
1.5
2.5
00+40 +120
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
SLA7024M and SLA7026M
Dimensions in Inches
(Based on 1" = 0.03937 mm)
Dimensions in Millimeters
NOTES: 1. Exact body and lead configuration at vendor’s option within limits shown.
2. Recommended mounting hardware torque: 4.34 – 5.79 lbf•ft (6 – 8 kgf•cm or 0.588 – 0.784 Nm).
3. The hatched area is exposed (electrically isolated) heat spreader.
4. Recommend use of metal-oxide-filled, alkyl-degenerated oil base, silicone grease (Dow Corning 340 or equivalent).
Dwg. MK-002-18 mm
118
31
±0.2
24.4
±0.2
16.4
±0.2
16
±0.2
9.9
±0.2
13
±0.2
ø
3.2
±0.15
1.68
±0.4
6.7
±0.5
3.0
4.0
±0.7
2.45
±0.2
4.8
±0.2
1.7
±0.1
3.2
±0.15
x 3.8
31.3
±0.2
0.65
+0.2
–0.1
0.55
+0.2
–0.1
Dwg. MK-002-18 in
118
1.22
±0.008
0.961
±0.008
0.646
±0.008
0.630
±0.008
0.512
±0.008
ø
0.126
±0.006
0.066
±0.016
0.264
±0.020
0.118
0.157
±0.028
0.096
±0.008
0.189
±0.008
0.067
±0.004
0.126
±0.006
x 0.150
1.232
±0.008
0.026
+0.008
–0.004
0.022
+0.008
–0.004
0.390
±0.008
TM
MicroSystems, Inc.
TM
A
A
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM, UNIPOLAR STEPPER
MOTOR CONTROLLER/DRIVERS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Dwg. MK-005-15 in
115
1.22
±0.008
0.402
±0.008
0.080
±0.004
0.264
±0.020
0.118
0.157
±0.028
0.057
±0.006
0.157
±0.008
0.098
±0.008
1.24
MAX.
0.026
+0.008
–0.004
0.022
+0.008
–0.004
0.335
MAX.
30°
SMA7029M
Dimensions in Inches
(Based on 1" = 0.03937 mm)
Dimensions in Millimeters
NOTE: Exact body and lead configuration at vendor’s option within limits shown.
Dwg. MK-005-15 mm
115
31±0.2
10.2
±0.2
2.03
±0.1
6.7
±0.5
3.0
4.0
±0.7
1.45
±0.15
4.0
±0.2 2.5
±0.2
31.5 MAX.
0.65 +0.2
–0.1
0.55 +0.2
–0.1
8.5
MAX.
30°
Allegro MicroSystems, Inc. reserves the right to make, from
time to time, such departures from the detail specifications as
may be required to permit improvements in the design of its
products. Components made under military approvals will be in
accordance with the approval requirements.
The information included herein is believed to be accurate
and reliable. However, Allegro MicroSystems, Inc. assumes no
responsibility for its use; nor for any infringements of patents or
other rights of third parties which may result from its use.
