2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
sInternal
Block Diagram
IN
A
IN
B
6
1
5
V
S
8
14
10
15
1, 6, 10, 15pin
Description of pins
Reg
Reg
+
–
+
–
+
–
+
–
1pin
6pin
10pin
15pin
Excitation input
Active H
Active L
OUT A
OUT A
OUT A
OUT A
OUT B
OUT B
OUT B
OUT B
GND
A
GND
B
REF
A
REF
B
R
SA
7
2
3
4
12
13
11
R
SB
9
T
DA
sDiagram
of Standard External Circuit (Recommended Circuit Constants)
T
DB
V
CC
(46V max)
+
Excitation signal time chart
2-phase excitation
clock
IN
A
IN
B
0
H
L
1
H
H
2
L
H
3
L
L
0
H
L
1
H
H
1-2 phase excitation
V
b
(5V)
8
V
S
1
6
10
15
IN
A
2
11
C
1
C
2
T
dA
T
dB
R
SA
REF
A
REF
B
R
SB
7
3 13
9
C
3
Rs
Open
collector
C
4
Rs
G
A
4
5
IN
A
r
3
r
4
r
1
IN
B
G
B
12
14
IN
B
clock
IN
A
td
A
IN
B
td
B
0
H
L
L
L
1
H
L
L
H
2
H
L
H
L
3
H
H
H
L
4
L
L
H
L
5
L
L
H
H
6
L
L
L
L
7
L
H
L
L
0
H
L
L
L
1
H
L
L
H
2 3
H H
L H
H H
L L
r
2
q
tdA and tdB are signals before the inverter stage.
510Ω
100Ω (VR)
47kΩ
47kΩ
2.4kΩ
2.4kΩ
330 to 500pF
330 to 500pF
2200pF
2200pF
1.8Ω typ(7022MU)
(1 to 2W)
1Ω typ(7029M)
r
1
:
r
2
:
r
3
:
r
4
:
r
5
:
r
6
:
C
1
:
C
2
:
C
3
:
C
4
:
R
s
:
r
5
r
6
t
dA
t
dB
6
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
sExternal
Dimensions SLA7022MU/SLA7029M
(Unit: mm)
φ
3.2
±0.15
31
±0.2
24.4
±0.2
16.4
±0.2
φ
3.2
±0.15
×3.8
4.8
±0.2
1.7
±0.1
Epoxy resin package
16
±0.2
13
±0.2
9.9
±0.2
6.7
±0.5
R-End
+0.2
0.65
–0.1
+0.2
1.15
–0.1
9.7
–0.5
+1
1.6
±0.6
+0.2
0.55
–0.1
1.15
–0.1
14×P2.03
±0.4
=28.42
±0.8
+0.2
14×P2.03
±0.7
=28.42
±1.0
31.3
±0.2
4
±0.7
2.2
±0.4
6.3
±0.6
7.5
±0.6
1 2 3 · · · · · · · 15
12 3 · · · · · · · 15
Forming No. No.853
Forming No. No.855
sExternal
Dimensions SMA7022MU/SMA7029MA
+0.2
0.55
–0.1
0.65
–0.1
+0.2
(3)
3
±0.6
2.45
±0.2
4.6
±0.6
Part No.
Lot No.
(Unit: mm)
Epoxy resin package
31
±0.2
10.2
±0.2
30°
4
±0.2
2.5
±0.2
3
±0.6
1.2
±0.1
(5.9)
(7.5)
1.6
±0.6
0.62
±0.1
1.16
±0.15
P2.03
±0.1
×14=28.42
12 3 · · · · · · · 15
1 2 3 · · · · · · · 15
(4.6)
0.55
–0.1
+0.2
8.5max
Lot No.
Part No.
1.45
±0.15
6.7
±0.5
(9.7)
+0.2
0.65
–0.1
1.16
+0.2
–0.1
P2.03
±0.1
×14=28.42
31.3
+0.2
+0.2
0.55
–0.1
4
±0.7
Forming No. No.1054
(3)
Forming No. No.1055
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
7
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
Application Notes
sDetermining
the Output Current
Fig. 1 shows the waveform of the output current (motor coil cur-
rent). The method of determining the peak value of the output
current (I
O
) based on this waveform is shown below.
(Parameters for determining the output current I
O
)
V
b
: Reference supply voltage
r
1
,r
2
: Voltage-divider resistors for the reference supply voltage
R
S
: Current sense resistor
(1) Normal rotation mode
I
O
is determined as follows when current flows at the maximum
level during motor rotation. (See Fig.2.)
V
b
................................................................
r
2
(1)
I
O
≅
•
r
1
+r
2
R
S
(2) Power down mode
The circuit in Fig.3 (rx and Tr) is added in order to decrease the
coil current. I
O
is then determined as follows.
I
OPD
≅
1+
1
r
1
(r
2
+r
X
)
r
2
•
r
X
•
Fig. 1 Waveform of coil current (Phase A excitation ON)
I
O
Phase A
0
Phase A
Fig. 2 Normal mode
V
b
(5
V
)
r
1
r
5
r
2
C
3
3,(13)
7,(9)
R
S
r
6
V
b
......................................................... (2)
R
S
Equation (2) can be modified to obtain equation to determine rx.
1
r
X
=
1
1
V
b
−1 −
r
1
R
s
•
I
OPD
r
2
Fig. 4 and 5 show the graphs of equations (1) and (2) respec-
tively.
Fig. 3 Power down mode
V
b
(5
V
)
r
6
r
1
r
5
r
x
Power down
signal
T
r
R
S
r
2
C
3
7,(9)
3,(13)
Fig. 4 Output current I
O
vs. Current sense resistor R
S
4
Fig. 5 Output current I
OPD
vs. Variable current sense resistor rx
2.0
2
r
2
V
b
·
r
1
+r
2
R
S
r
1
=510Ω
r
2
=100Ω
r
x
=∞
V
b
=5V
I
O
=
Output current I
OPD
(A)
Output current I
O
(A)
3
1.5
R
S
=0.5Ω
1
· V
b
r
1
(r
2+
r
X
)
R
S
1+
r
2 ·
r
X
r
1
=510Ω
r
2
=100Ω
V
b
=5V
I
OPD
=
1.0
R
S
=0.8Ω
R
S
=1Ω
1
0.5
0
0
1
2
3
4
00
200
400
600
800
1000 1200
Current sense resistor R
S
(Ω)
Variable current sense resistor r
X
(Ω)
(NOTE)
Ringing noise is produced in the current sense resistor R
S
when
the MOSFET is switched ON and OFF by chopping. This noise
is also generated in feedback signals from R
S
which may there-
fore cause the comparator to malfunction. To prevent chopping
malfunctions, r
5
(r
6
) and C
3
(C
4
) are added to act as a noise filter.
However, when the values of these constants are increased,
the response from R
S
to the comparator becomes slow. Hence
the value of the output current I
O
is somewhat higher than the
calculated value.
8
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
sDetermining
the chopper frequency
Determining T
OFF
The SLA7000M and SMA7000M series are self-excited chop-
pers. The chopping OFF time T
OFF
is fixed by r
3
/C
1
and r
4
/C
2
connected to terminal Td.
T
OFF
can be calculated using the following formula:
2
2
T
OFF
≅−r
3
•
C
1
r
n
(1−
=−r
4
•
C
2
r
n
(1−
)
V
b
V
b
The circuit constants and the T
OFF
value shown below are rec-
ommended.
T
OFF
= 12
µ
s at r
3
=47kΩ, C
1
=500pF, V
b
=5V
Fig. 6 Chopper frequency vs. Motor coil resistance
60
15
Chopping frequency f (kHz)
1.0
50
ON time T
ON
(
µ
s)
40
30
V
CC
20
=2
4V
25
30
35
40
20
10
0
V
CC
V
=36
47kΩ
r
4
500pF
C
1
= C
2
=
T
OFF
=12
µ
s
R
S
=1Ω
L
m
=1~3ms
R
m
r
3
0
2
4 6
8 10 12 14 16
Motor coil resistance R
m
(Ω)
sChopper
frequency vs. Supply voltage
sChopper
frequency vs. Output current
50
50
40
40
f (kHz)
20
Motor : 23LM-C202
I
O
= 0.8A at V
CC
=24V
R
S
=1Ω
f (kHz)
30
30
20
Motor : 23LM-C202
V
CC
=24V
R
S
=1Ω
10
10
0
0
10
20
30
40
50
0
0
0.2
0.4
0.6
0.8
V
CC
(V)
I
O
(A)
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
9
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