2-Phase Stepper Motor Unipolar Driver ICs (2-Phase/1-2 Phase Excitation)
SLA7027MU/SLA7024M/SLA7026M
sThermal
Design
An outline of the method for calculating heat dissipation is shown be-
low.
(1) Obtain the value of P
H
that corresponds to the motor coil current
I
O
from Fig. 7 "Heat dissipation per phase P
H
vs. Output current I
O
."
Fig. 7 Heat dissipation per phase P
H
vs. Output current I
O
SLA7027MU
1.2
(2) The power dissipation Pdiss is obtained using the following formula.
2-phase excitation: P
diss
2P
H
+0.015×V
S
(W)
3
P
H
+0.015×V
S
(W)
1-2 phase excitation: P
diss
2
(3) Obtain the temperature rise that corresponds to the calcu-
lated value of Pdiss from Fig. 8 "Temperature rise."
SLA7026M
4.0
Heat dissipation per phase P
H
(W)
Heat dissipation per phase P
H
(W)
1
=4
4V
0.8
0.4
1.0
0.2
0
0
0.2
0.4
0.6
0.8
1.0
0
0
Output current
I
O
(A)
1.0
2.0
Output current I
O
(A)
36
V
15
V
24
V
T
j
C
T
0.6
V
24
2.0
V
C
C
4V
=4
CC
V
V
36
3.0
15
V
Motor : 23LM-C202
Holding mode
Motor : 23PM-C503
Holding mode
3.0
Fig. 8 Temperature rise
1.2
Heat dissipation per phase P
H
(W)
SLA7024M
150
1.0
0.8
0.6
0.4
0.2
0
0
=44
V
24V
∆T
j–a
∆T
C–a
(°C)
V
36
100
Motor : 23LM-C004
V
Holding mode
15
V
CC
Natural cooling
Without heatsink
50
0
0.2
0.4
0.6
0.8
Output current I
O
(A)
1.0
0
1
2
3
Total Power (W)
4
5
Thermal characteristics
SLA7027MU
35
30
25
20
15
10
5
0
200
SLA7026M
50
Case temperature rise
∆T
C–a
(°C)
Case temperature rise
∆T
C–a
(°C)
Without heatsink
Natural cooling
Without heatsink
Natural cooling
40
T
C
( 4 pin)
Motor : PH265-01B
Motor current I
O
=0.8A
T
a
=25°C
V
CC
=24V, V
S
=24V
2-phase excitation
30
T
C
( 4 pin)
Motor : 23PM-C705
Motor current I
O
=1.5A
T
a
=25°C
V
CC
=24V, V
S
=24V
2-phase excitation
20
10
500
1K
0
100
500
1K
5K
Response frequency
(pps)
Response frequency
(pps)
30
SLA7024M
Without heatsink
Natural cooling
Case temperature rise
∆T
C–a
(°C)
25
20
T
C
( 4 pin)
15
10
5
0
200
Motor : PH265-01B
Motor current I
O
=0.8A
T
a
=25°C
V
CC
=24V, V
S
=24V
2-phase excitation
500
1K
Response frequency
(pps)
SLA7027MU/SLA7024M/SLA7026M
25
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