6
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
s
Internal Block Diagram
s
Diagram of Standard External Circuit (Recommended Circuit Constants)
6
Reg
Reg
1
5
8
V
S
14
IN
B
IN
A
7
R
SA
2
3
4
12
13
11
T
DA
REF
A
GND
A
GND
B
REF
B
T
DB
R
SB
9
10
15
+
+
+
+
1, 6, 10, 15pin
Description of pins
Excitation input
Active H
OUT A
OUT A
OUT B
OUT B
1pin
6pin
10pin
15pin
Active L
OUT A
OUT A
OUT B
OUT B
8
1
6
10
15
V
S
R
SA
REF
A
REF
B
R
SB
G
A
G
B
7
3 13
9
4
12
C
4
r
6
r
5
r
2
r
1
r
4
r
3
C
1
C
2
T
dA
T
dB
IN
A
IN
B
IN
A
IN
B
5
14
+
V
CC
(46V max)
V
b
(5V)
Rs
Rs
C
3
11
2
Open
collector
t
dA
t
dB
Excitation signal time chart
2-phase excitation
clock
0
1
2
3
0
1
IN
A
H
H
L
L
H
H
IN
B
L
H
H
L
L
H
1-2 phase excitation
clock 0
1
2
3
4
5
6
7
0
1
2 3
IN
A
H H H H
L
L
L
L
H H H H
td
A
L
L
L
H
L
L
L
H L
L
L
H
IN
B
L
L
H H H H
L
L
L
L
H
H
td
B
L H L
L
L
H
L
L
L
H
L
L
q
tdA and tdB are signals before the inverter stage.
r
1
: 510
r
2
: 100
(VR)
r
3
: 47k
r
4
: 47k
r
5
: 2.4k
r
6
: 2.4k
C
1
: 330 to 500pF
C
2
: 330 to 500pF
C
3
: 2200pF
C
4
: 2200pF
R
s
: 1.8
typ(7022MU)
1
typ(7029M)
(1 to 2W)
7
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
s
External Dimensions SLA7022MU/SLA7029M
(Unit: mm)
31
0.2
24.4
0.2
16.4
0.2
3.2
0.15
16
0.2
13
0.2
9.9
0.2
Part No.
Lot No.
3.2
0.15
3.8
4.8
0.2
1.7
0.1
2.45
0.2
R-End
6.7
0.5
9.7
+1
0.5
(3)
0.55
+0.2
0.1
4
0.7
1.15
+0.2
0.1
14
P2.03
0.7
=28.42
1.0
0.65
+0.2
0.1
31.3
0.2
Forming No. No.853
1 2 3 15
12 3 15
Forming No. No.855
14
P2.03
0.4
=28.42
0.8
0.65
+0.2
0.1
3
0.6
0.55
+0.2
0.1
2.2
0.4
6.3
0.6
7.5
0.6
4.6
0.6
1.6
0.6
Epoxy resin package
1.15
+0.2
0.1
(Unit: mm)
s
External Dimensions SMA7022MU/SMA7029MA
Forming No. No.1054
31
0.2
Part No.
Lot No.
4
0.2
2.5
0.2
1.45
0.15
6.7
0.5
(9.7)
(3)
0.55
+0.2
0.1
4
0.7
P2.03
0.1
14=28.42
0.65
+0.2
0.1
1 2 3 15
12 3 15
P2.03
0.1
14=28.42
1.16
0.15
3
0.6
0.55
+0.2
0.1
1.2
0.1
(5.9)
(4.6)
1.6
0.6
1.16
+0.2
0.1
30
0.62
0.1
(7.5)
Epoxy resin package
8.5ma
x
10.2
0.2
31.3
+0.2
Forming No. No.1055
8
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
s
Determining 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.)
(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.
Equation (2) can be modified to obtain equation to determine rx.
Fig. 4 and 5 show the graphs of equations (1) and (2) respec-
tively.
(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.
R
S
C
3
r
2
r
1
r
6
r
5
V
b
(5
V
)
7,(9)
3,(13)
Fig. 2 Normal mode
0
Phase A
Phase A
I
O
Fig. 1 Waveform of coil current (Phase A excitation ON)
R
S
C
3
r
2
r
1
r
6
r
5
V
b
(5
V
)
7,(9)
3,(13)
r
x
T
r
Power down
signal
Fig. 3 Power down mode
4
3
2
1
0
0
1
2
3
4
Current sense resistor R
S
(
)
Output current I
O
(A)
I
O
=
r
1
+r
2
R
S
r
1
=510
r
2
=100
r
x
=
V
b
=5V
r
2
V
b
Fig. 4 Output current I
O
vs. Current sense resistor R
S
Fig. 5 Output current I
OPD
vs. Variable current sense resistor rx
2.0
1.5
1.0
0.5
00
200
400
600
800
Variable current sense resistor r
X
(
)
Output current I
OPD
(A)
1000
1200
R
S
=0.5
R
S
=0.8
R
S
=1
I
OPD
=
1+ R
S
r
1
=510
r
2
=100
V
b
=5V
1
V
b
r
1
(r
2+
r
X
)
r
2
r
X
Application Notes
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.
r
X
=
1
V
b
R
s
I
OPD
1
r
1
-
1
-
1
r
2
................................................................ (1)
I
O
r
2
r
1
+r
2
V
b
R
S
......................................................... (2)
I
OPD
1
r
1
(r
2
+r
X
)
r
2
r
X
V
b
R
S
1+
9
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
SLA7022MU/SLA7029M/SMA7022MU/SMA7029M
2-Phase Stepper Motor Unipolar Driver ICs (2-Phase Excitation)
s
Determining 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:
The circuit constants and the T
OFF
value shown below are rec-
ommended.
T
OFF
= 12
s at r
3
=47k
, C
1
=500pF, V
b
=5V
60
50
40
30
20
10
0
0
2
4
6
8
10 12
14
16
15
20
25
30
35
40
Motor coil resistance R
m
(
)
ON time T
ON
( s)
V
CC
=2
4V
V
CC
=36V
Chopping frequency f (kHz)
T
OFF
=12 s
R
S
=1
L
m
=1~3ms
R
m
= =
r
3
C
1
r
4
C
2
47k
500pF
Fig. 6 Chopper frequency vs. Motor coil resistance
s
Chopper frequency vs. Supply voltage
0
f (kHz)
V
CC
(V)
50
40
30
20
10
0
10
20
30
40
50
Motor : 23LM-C202
I
O
= 0.8A at V
CC
=24V
R
S
=1
s
Chopper frequency vs. Output current
0
f (kHz)
I
O
(A)
50
40
30
20
10
0
0.2
0.4
0.6
0.8
1.0
Motor : 23LM-C202
V
CC
=24V
R
S
=1
T
OFF
-
r
3
C
1 n
(1
-
=
-
r
4
C
2
n
(1
-
)
r
r
2
V
b
2
V
b
PDF 
ZIP