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 advances power multi-chip modules (PMCMs™) toward the complete
integration of motion control. Highly automated manufacturing techniques 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.
SMA7029M
2
REFERENCE A
3
GROUND A
4
IN A
5
OUT A
6
SENSE A
7
8
SENSE B
9
OUT B
10
OFF DELAY B
11
GROUND B
12
REFERENCE B
13
IN B
14
OUT B
+
15
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.
VCC
VREF
CONTROL/LOGIC
CNTRL SPLY
VREF
+
1
OFF DELAYA
CONTROL/LOGIC
OUTA
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 networks. The RC components limit the OFF interval and control current
decay. Inputs are compatible with 5 V logic and microprocessors.
Dwg. PK-007
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
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
■ 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
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
™
Data Sheet
28201
SLA7024M, SLA7026M,
AND SMA7029M
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
SLA7024M and SLA7026M FUNCTIONAL BLOCK DIAGRAM
CONTROL
SUPPLY
IN A/B IN
A/B
OUT A/B
OUT A/B
7
6
5
8
1
12
17
16
18
11
VCC
REFERENCE
REG.
+
3
14
+
13
15
2
4
OFF-TIME
DELAY
10
9
GROUND
SENSE
CHANNEL A PIN NUMBERS
CHANNEL B PIN NUMBERS
Dwg. FK-005
Note that channels A and B are electrically isolated.
SMA7029M FUNCTIONAL BLOCK DIAGRAM
CONTROL
SUPPLY
IN A/B
OUT A/B
8
5
1
6
8
14
10
15
OUT A/B
V CC
REFERENCE
REG.
+
3
13
+
11
12
2
4
OFF-TIME
DELAY
GROUND
9
7
CHANNEL A PIN NUMBERS
CHANNEL B PIN NUMBERS
SENSE
Dwg. FK-005-1
Note that except for the control supply, channels A and B are electrically isolated.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1994 Allegro MicroSystems, Inc.
™
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
SLA7024M and SLA7026M
25
20
PREFIX 'SLA'
R θJM = 5.0°C/W
15
CONTROL/LOGIC
CONTROL/LOGIC
PREFIX 'SMA'
RθJM = 6.0°C/W
VCC
VCC
VREF
10
VREF
+
+
REFERENCE B
15
16
17
18
OUT B
14
IN B
13
IN B
12
GROUND B
11
OFF DELAY B
Dwg. GK-018
10
CNTRL SPLY B
9
OUT B
8
SENSE B
7
SENSEA
150
6
OUT A
125
5
CNTRL SPLY A
75
100
TEMPERATURE in ° C
4
IN A
50
3
IN A
25
2
GROUND A
0
1
REFERENCEA
PREFIX 'SMA'
R θJA = 31°C/W
OFF DELAY A
PREFIX 'SLA'
R θJA = 28°C/W
5
OUT A
ALLOWABLE PACKAGE POWER DISSIPATION in WATTS
ALLOWABLE PACKAGE
POWER DISSIPATION
Dwg. PK-006
ELECTRICAL CHARACTERISTICS at TA = +25°C
Limits
Characteristic
FET Leakage Current
FET ON Voltage
FET ON Resistance
Body Diode
Symbol
IDSS
VDS(ON)
rDS(on)
VSD
Forward Voltage
Test Conditions
Min
Typ
Max
Units
VDS = 100 V, VCC = 44 V
—
—
4.0
mA
(SLA7024M & SMA7029M) VCC = 14 V, IOUT = 1 A
—
—
600
mV
(SLA7026M) VCC = 14 V, IOUT = 3 A
—
—
850
mV
(SLA7024M & SMA7029M) VCC = 14 V, IOUT = 1 A
—
—
600
mΩ
(SLA7026M) VCC = 14 V, IOUT = 3 A
—
—
285
mΩ
(SLA7024M & SMA7029M) IOUT = –1 A
—
0.9
1.5
V
(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
IIN(H)
VCC = 44 V, VIN = 2.4 V
—
—
40
µA
IIN(L)
VIN = 0.4 V
—
—
-800
µA
VIN(H)
2.0
—
—
V
VIN(L)
—
—
0.8
V
Input Current
Input Voltage
NOTE: Negative current is defined as coming out of (sourcing) the specified device pin.
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
TYPICAL STEPPER MOTOR APPLICATIONS
(Half of Each Device Shown)
SLA7024M and SLA7026M
V BB
A
IN B
IN B
A
OUT B
12
17
V
16
OUT B
18
11
CC
REG.
R 1 510 Ω
V b +5 V
TO
CHANNEL
A
VREF
+
R 2 100 Ω
14
+
2.4 kΩ
R
5
td
SENSE
13
15
10
+5 V
47 kΩ
R
3
C 3 2200 pF
470 pF
C1
R
S
≤1 Ω
Dwg. EK-008
TRUTH TABLES
(Device Types as Designated)
WAVE DRIVE (FULL STEP)
for SLA7024M and SLA7026M
Sequence
Input A
Input A
Input B
Input B
Output ON
0
H
L
L
L
A
1
L
L
H
L
B
2-PHASE (FULL STEP) OPERATION
for SLA7024M and SLA7026M
2
L
H
L
L
A
3
L
L
L
H
B
0
H
L
L
L
A
Sequence
Input A
Input A
Input B
Input B
Outputs ON
0
H
L
H
L
AB
1
L
H
H
L
AB
2
L
H
L
H
AB
3
H
L
L
H
AB
0
H
L
H
L
AB
HALF-STEP OPERATION (2-1-2 SEQUENCE)
for SLA7024M, SLA7026M, and SMA7029M
Sequence
Input A
0
H
1
H
2
L
3
L
4
L
5
L
6
L
7
H
0
H
Input A or tdA*
Input B
L
L
L
H
L
H
H
H
H
L
H
L
L
L
L
L
L
L
Input B or tdB*
L
L
L
L
L
H
H
H
L
Output(s) ON
A
AB
B
AB
A
AB
B
AB
A
*Logic signals to external open-collector inverter connected to tdA and tdB.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
TYPICAL STEPPER MOTOR APPLICATIONS
(Half of Device Shown)
SMA7029M
V BB
A
IN B
A
OUT B
8
14
OUT B
10
15
VCC
REG.
R 1 510 Ω
V b +5 V
TO
CHANNEL
A
VREF
R 2 100 Ω
13
+
+
2.4 kΩ
R
5
td
SENSE
11
12
9
C1
470 pF
+5 V
R 3 47 kΩ
OPEN-COLLECTOR
INVERTER
C 3 2200 pF
R
S
≤1 Ω
Dwg. EK-008-1
TRUTH TABLES
(SMA7029M Only)
WAVE DRIVE (FULL STEP) for SMA7029M
Sequence
Input A
Input tdA*
Input B
Input tdB*
Output ON
0
H
L
L
L
A
1
L
L
H
L
B
2
L
H
L
L
A
3
L
L
L
H
B
0
H
L
L
L
A
*Logic signals to external open-collector inverter connected to tdA and tdB.
2- PHASE (FULL STEP) OPERATION
for SMA7029M
Sequence
Input A
Input B
Outputs ON
0
H
L
AB
1
H
H
AB
2
L
H
AB
3
L
L
AB
0
H
L
AB
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
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:
VREF
IOUT ≈
(1)
RS
or, if VREF is not known
IOUT ≈
R2
R1 + R2
•
Vb
(2)
RS
I OUT
PHASE A
0
PHASE A
Dwg. WK-001
FIGURE 1. PHASE A COIL CURRENT WAVEFORM
VCC
Vb
INPUT
V BB
B
R3
R1
B
C1
R5
R2
td
A
V REF
PEAK
CURRENT
DETECTOR
PWM
OFF-TIME
CONTROL
CONTROL
LOGIC
C3
A
CURRENT
CONTROL
&
RECIRCULATING
CURRENT
CONTROL
SENSE
R
S
Dwg. EK-009
FIGURE 2.
PWM CONTROL (RUN MODE)
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 R1, R2, and Vb (VREF ≈ 0.82 V), Figure 3 illustrates
output current as a function of current-sensing resistance (RS).
OUTPUT TRIP CURRENT in AMPERES
3.0
SLA7026M MAX.
2.5
R1 = 510 Ω
R2 = 100 Ω
RX = ∞
2.0
Vb = 5 V
1.5
1.0
SLA7024M & SMA7029M MAX.
0.5
0
0
0.5
1.0
1.5
2.0
2.5
3.0
CURRENT-SENSING RESISTANCE in OHMS
3.5
4.0
Dwg. GK-014
FIGURE 3. CURRENT-SENSING RESISTANCE
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 ≈
or
IHOLD ≈
R2 RX
R1 R2 + R1 RX + R2 RX
R2Õ
R1 + R2Õ
•
•
Vb
(3)
RS
Vb
(4)
RS
where R2Õ= the equivalent value of R2 and RX in parallel.
Vb
R1
RX
R5
V REF
HOLD
SENSE
R2
C3
RS
Dwg. EK-010
FIGURE 4. HOLD CURRENT MODE
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
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 currentsensing resistance (RS).
1.0
OUTPUT TRIP CURRENT in AMPERES
RS = 0.8 Ω
0.8
RS = 1.0 Ω
0.6
0.4
R1 = 510 Ω
R2 = 100 Ω
Vb = 5 V
0.2
0
0
100
200
300
400
500
HOLDING-CURRENT RESISTANCE in OHMS
600
Dwg. GK-015
FIGURE 5A. HOLD-CURRENT RESISTANCE
(SLA7024M and SMA7029M)
3.0
R1 = 510 Ω
R2 = 100 Ω
2.5
OUTPUT TRIP CURRENT in AMPERES
Vb = 5 V
RS = 0.33 Ω
2.0
RS = 0.47 Ω
1.5
1.0
0.5
0
0
100
200
300
400
500
600
700
800
HOLDING-CURRENT RESISTANCE in OHMS
Dwg. GK-015-1
FIGURE 5B. HOLD-CURRENT RESISTANCE (SLA7026M)
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.
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.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
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:
2
tOFF ≈ -R3 • C1 • logn (1 - )
(5)
Vb
Recommended circuit constants and tOFF are:
Vb = 5 V
R3 = 47 kΩ
C1 = 470 pF
tOFF = 12 µs
40
ON TIME in µs
RS = 1 Ω
L/R = 1 to 3 ms
20
VCC = 24 V
30
25
30
20
VCC = 36 V
35
40
10
CHOPPING FREQUENCY in kHz
50
0
0
2
4
8
6
10
MOTOR RESISTANCE in OHMS
12
14
Dwg. GK-016
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)
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
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 exceeds +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.
NORMALIZED FET ON RESISTANCE
2.5
2.0
1.5
1.0
0.5
0
-40
0
+40
+80
JUNCTION TEMPERATURE in °C
+120
+160
Dwg. GK-017
FIGURE 8. NORMALIZED ON RESISTANCE
vs TEMPERATURE
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
Dimensions in Inches
(for reference only)
0.126 ±0.006 x 0.150
1.22 ±0.008
0.126
±0.006
0.961 ±0.008
ø
0.189
±0.008
0.646
0.067
0.512
±0.008
0.390
±0.008
0.630
±0.004
±0.008
±0.008
0.096
±0.008
0.264
±0.020
0.118
1
18
1.232 ±0.008
+0.008
0.026 –0.004
0.022 +0.008
–0.004
0.157
0.066
±0.028
±0.016
Dimensions in Millimeters
(controlling dimensions)
3.2 ±0.15 x 3.8
31±0.2
3.2
±0.15
24.4 ±0.2
ø
4.8
±0.2
16.4 ±0.2
1.7
13 ±0.2
9.9 ±0.2
16 ±0.2
±0.1
2.45
±0.2
6.7
±0.5
3.0
1
18
0.55
31.3 ±0.2
+0.2
0.65 –0.1
1.68
±0.4
+0.2
–0.1
4.0
±0.7
Dwg. MK-002-18 mm
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).
SLA7024M, SLA7026M, AND SMA7029M
HIGH-CURRENT PWM,
UNIPOLAR STEPPER MOTOR
CONTROLLER/DRIVERS
SMA7029M
Dimensions in Inches
(for reference only)
1.24 MAX.
0.157
±0.008
0.098
0.335
MAX.
±0.008
±0.008
0.402
1.22 ±0.008
30°
0.057
±0.006
0.264
±0.020
0.118
1
0.022 +0.008
–0.004
15
+0.008
0.026 –0.004
0.157
0.080
±0.028
±0.004
Dimensions in Millimeters
(controlling dimensions)
31.5 MAX.
4.0
±0.2
2.5
8.5
MAX.
±0.2
±0.2
10.2
31±0.2
30°
1.45
±0.15
6.7
±0.5
3.0
1
15
0.55 +0.2
–0.1
+0.2
0.65 –0.1
2.03
±0.1
4.0
±0.7
Dwg. MK-005-15 mm
NOTE: Exact body and lead configuration at vendor’s option within limits shown.
The products described here are manufactured in Japan by Sanken Electric Co.,
Ltd. for sale by Allegro MicroSystems, Inc.
Sanken Electric Co., Ltd. and Allegro MicroSystems, Inc. reserve 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 their products.
The information included herein is believed to be accurate and reliable.
However, Sanken Electric Co., Ltd. and Allegro MicroSystems, Inc. assume no
responsibility for its use; nor for any infringements of patents or other rights of third
parties which may result from its use.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
™