1-1-2 Switching Mode Regulator ICs
SI-8400L/8500L Series
Separate Excitation Switching Mode Regulator ICs with Coil
■Features
• Switching ICs/Coil combined type
• Requires only 2 discrete components
• Low switching noise
• No heatsink required
• Built-in overcurrent and thermal protection
circuits
• Built-in soft start circuit (Output ON/OFF
available)...SI-8500L Series
■Lineup
Part Number
V
O
(V)
I
O
(A)
SI-8401L
5.0
0.5
SI-8501L
5.0
1.0
■Absolute
Maximum Ratings
Parameter
DC Input Voltage
Power Dissipation
Junction Temperature
Storage Temperature
Symbol
V
IN
P
D
T
j
T
stg
1.25
+100
–25 to +85
Ratings
SI-8400L
35
3
SI-8500L
Unit
V
W
°C
°C
■Applications
• Telephone power supplies
• Onboard local power supplies
■Recommended
Operating Conditions
Parameter
DC Input Voltage Range
Output Current Range
Operating Temperature Range
Symbol
V
IN
I
O
T
op
Ratings
SI-8401L
7 to 33
0 to 0.5
–20 to +85
Unit
V
A
°C
Parameter
DC Input Voltage Range
Output Current Range
Operating Temperature Range
Symbol
V
IN
I
O
T
op
Ratings
SI-8501L
7 to 33
0 to 1.0
–20 to +85
Unit
V
A
°C
■Electrical
Characteristics
Ratings
Parameter
Symbol
min.
Output Voltage
Efficiency
Oscillation Frequency
Line Regulation
Load Regulation
Temperature Coefficient of Output Voltage
Switching Ripple
Voltage (C
2
=470
µ
F)
Overcurrent Protection
Starting Current
V
O
Conditions
4.80
SI-8401L
typ.
5.00
V
IN
=20V, I
O
=0.3A
80
V
IN
=20V, I
O
=0.3A
60
V
IN
=20V, I
O
=0.3A
80
V
IN
=10 to 30V, I
O
=0.3A
30
V
IN
=20V, I
O
=0.1 to 0.4A
±0.5
20
V
IN
=20V, I
O
=0.3A
0.55
V
IN
=10V
40
40
100
max.
5.20
(T
a
=25°C)
Unit
V
%
kH
Z
mV
mV
mV/°C
mV
p-p
A
(T
a
=25°C)
η
Conditions
f
Conditions
∆V
OLINE
Conditions
∆V
OLOAD
Conditions
∆V
O
/∆T
a
∆V
r
Conditions
I
S1
Conditions
Ratings
Parameter
Symbol
min.
Output Voltage
Efficiency
Oscillation Frequency
Line Regulation
Load Regulation
Temperature Coefficient of Output Voltage
Switching Ripple
Voltage (C
2
=470
µ
F)
Overcurrent Protection
Starting Current
V
O
Conditions
4.80
SI-8501L
typ.
5.00
V
IN
=20V, I
O
=0.5A
83
V
IN
=20V, I
O
=0.5A
60
V
IN
=20V, I
O
=0.5A
70
V
IN
=10 to 30V, I
O
=0.5A
30
V
IN
=20V, I
O
=0.2 to 0.8A
±0.5
45
V
IN
=20V, I
O
=0.5A
1.1
V
IN
=18V
A
mV
p-p
55
mV
mV/°C
130
mV
kH
Z
%
max.
5.20
V
Unit
η
Conditions
f
Conditions
∆V
OLINE
Conditions
∆V
OLOAD
Conditions
∆V
O
/∆T
a
∆V
r
Conditions
I
S1
Conditions
86
ICs
SI-8400L/8500L Series
■External
Dimensions (Non-package type [EI-12.5 core/EI-19 core])
SI-8400L
V
IN
y
V
IN
r
12
±0.5
(Unit : mm)
SI-8500L
L
IN
r
e
L
IN
Vo
q
14.5
±0.5
w
GND
Pin 1 marking
Not encapsulated in a plastic
package
Product Mass: Approx. 5.1g
26
±0.1
SK
10
±0.2
13.2
±0.6
q w e
V
OUT
SS GND
±0.1
26
Pin1 marking
Not encapsulated in a plastic
package
Product Mass: Approx. 14.5g
φ
0.6
4
3.7
18
(2.17)
(10.16)
4.7
φ
0.8max.
±0.6
(7.62)
(2.19)
18
2
■Block
Diagram
SI-8400L
3
4
V
IN
Reg.
OSC
Reset
OCP
Latch
&
Drive
TSD
Di
1
Amp.
Amp.
SI-8500L
L
IN
L
1
1
V
O
6
V
IN
Reg.
OSC
Reset
OCP
Latch
&
Drive
TSD
Di
1
MIC
1
4
L
IN
L
1
1
V
O
MIC
1
Comp.
Comp.
V
REF
V
REF
2
GND
2
S.S.
3
GND
■Typical
Connection Diagram
V
IN
V
IN
SI-8400L
GND
2
V
OUT
L
IN
3
N.C
V
O
V
IN
V
IN
SI-8500L
S.S
2
C
3
GND
3
V
OUT
L
IN
4
N.C
GND
V
O
4
+
C
1
220
µ
F
1
+
6
+
C
1
µ
F
470
1
+
C
2
470
µ
F
GND
C
2
470
µ
F
GND
GND
C
3
is necessary only for using soft start function.
■T
a
-P
D
Characteristics
1.5
3.0
SI-8400L
SI-8500L
P
D
=V
O
•I
O
100
–1
ηχ
Power Dissipation P
D
(W)
Power Dissipation P
D
(W)
1.0
2.0
V
O
: Output voltage
I
O
: Output current
ηχ
: Efficiency (%)
The efficiency depends on the input voltage
and the output current. Therefore, obtain the
value from the efficiency graphs and substi-
tute the percentage in the formula above.
0.5
1.0
0
0
25
50
75
100
0
0
25
50
75
100
Ambient Temperature T
a
(°C)
Ambient Temperature T
a
(°C)
ICs
87
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