72
Parameter
DC Input Voltage
Power Dissipation
Junction Temperature
Storage Temperature
SW Terminal Applied Reverse Voltage
Thermal Resistance(junction to case)
Parameter
DC Input Voltage Range
Output Current Range
Operating Junction Temperature Range
Symbol
V
IN
P
D
T
j
T
stg
V
SW
R
th(j-c)
s
Features
Surface-mount package
Output current: 0.4 to 0.5A
High efficiency: 75 to 89%
Requires only 4 external components
Phase correction and output voltage adjustment performed internally
Built-in reference oscillator (60kHz)
Built-in overcurrent and thermal protection circuits
s
Applications
Power supplies for telecommunication equipment
Onboard local power supplies
s
Lineup
SAI Series
Surface-Mount, Separate Excitation Switching Type
q
SAI Series
Unit
V
A
C
Symbol
V
IN
I
O
T
jop
s
Absolute Maximum Ratings
s
Recommended Operating Conditions
Part Number
SAI01
SAI02
SAI03
SAI04
SAI06
V
O
(V)
5.0
3.3
12.0
15.0
9.0
I
O
(A)
0.5
0.4
Ratings
35
0.75
+125
40 to +125
1
20
Unit
V
W
C
C
V
C/W
Ratings
SAI01
SAI02
SAI03
SAI04
SAI06
7 to 33
5.3 to 28
15 to 33
18 to 33
12 to 33
0 to 0.5
0 to 0.4
30 to +125
74
s
Selecting External Components
1. Inductor L
1
1) It must be suited for switching regulators.
Do not use inductors as noise filters as they generate excessive heat.
2) It must have the appropriate inductance value.
If the inductance is too small (150
H or lower), abnormal oscillation may occur causing operation problems in the overcurrent protection
circuit within the rated current range.
3) The rated current must be satisfied.
If the rated current is exceeded, magnetic saturation leads to overcurrent.
2. Capacitors C
1
and C
2
1) They must satisfy the withstand voltage and allowable ripple current.
Exceeding the ratings of these capacitors or using them without derating shortens their service lives and may also cause abnormal
oscillation of the IC.
2) C
2
must be a low-impedance type capacitor.
A low-impedance type capacitor is recommended for C
2
to ensure minimum ripple voltage and stable switching operation.
3. Diode D
1
The Sanken SFPB54 diode is recommended for D
1
. If you intended to use an equivalent diode, be sure to use a Schottky Barrier diode and
make sure that the reverse voltage applied to terminal 2 of the IC does not exceed the value (1V) given in the absolute maximum ratings. If
you use a fast recovery diode or any other diode, application of a reverse voltage generated from the recovery or ON voltage of the diode may
damage the IC.
Application
Variable output voltage
Output voltage can be adjusted in the same way as SI-8000S in page 85.
s
Example of Printed Circuit Board
a) For optimum operation, there must be only
one GND line originating from terminal 4
and each component must be connected
with the shortest possible wiring.
b) To prevent heating of the IC, it is best to
make the GND pattern as large as pos-
sible since the internal frame and termi-
nal 4 (GND) are connected to each other.
s
T
a
-P
D
Characteristics
The efficiency depends on the input voltage and the out-
put current. Thus, obtain the value from the efficiency
graph on page 75 and substitute the percentage in the
formula above.
V
O
:Output voltage
I
O
:Output current
x :Efficiency (%)
V
F
:Diode forward voltage
SFPB54-0.3V
Thermal design for D
1
must be considered separately.
+
+
V
IN
DI
1
C
1
L
1
C
2
GND
SW
V
O
1
2
3
4
SAI
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
30
0
25
50
75
100
125
Power Dissipation P
D
(W)
Ambient Temperature T
a
(
C)
Glass epoxy
substrate
(95
69
1.2)
Natural cooling
q
SAI Series
P
D
=V
O
I
O
100
1
V
F
I
O
1
V
O
V
IN
75
s
Typical Characteristics
Rise Characteristics(SAI01)
Efficiency Characteristics(SAI01)
Load Regulation(SAI01)
Temperature Characteristics(SAI01)
Overcurrent Protection Characteristics(SAI01)
Thermal Protection Characteristics(SAI01)
Rise Characteristics(SAI03)
Efficiency Characteristics(SAI03)
Load Regulation(SAI03)
100
90
80
70
60
50
40
0
Efficiency
(%)
0
0.1
0.2
0.3
Output Current I
O
(A)
0.4
0.5
T
a
=25
C
V
IN
=7V
20V
33V
10V
25V
5.3
5.2
5.1
5.0
4.9
4.8
4.7
0
V
IN
=33V
20V
10V
7V
Output Voltage V
O
(V)
0
0.1
0.2
0.3
Output Current I
O
(A)
0.4
0.5
T
a
=25
C
100
90
80
70
60
50
40
0
Efficiency
(%) Frequency f (kHz)
Output Voltage V
O
(V)
50
0
50
Ambient Temperature T
a
(
C)
100
150
V
IN
=20V, I
O
=0.3A
V
O
f
5.3
5.2
5.1
5.0
4.9
4.8
4.7
0
0
100
90
80
70
60
50
40
0
0.1
0.2
Output Current I
O
(A)
0.3
0.4
T
a
=25
C
V
IN
=15V
24V
33V
Efficiency
(%)
0
12.3
12.2
12.1
12.0
11.9
11.8
0
0.1
0.2
Output Current I
O
(A)
0.3
0.4
Output Voltage V
O
(V)
T
a
=25
C
V
IN
=33V
24V
20V
15V
Output Voltage V
O
(V)
6
5
4
3
2
1
0
0
0.5
1.0
Output Current I
O
(A)
1.5
2.0
T
a
=25
C
V
IN
=7V
20V
33V
q
SAI Series
Note on Thermal Protection:
The thermal protection circuit is intended for pro-
tection against heat during instantaneous short-
circuiting. Its operation is not guaranteed for short-
circuiting over extended periods of time.
6
5
4
3
2
1
0
0
2
4
6
Input Voltage V
IN
(V)
0.1A
Output Voltage V
O
(V)
8
10
T
a
=25
C
I
O
=0A
0.5A
0
6
5
4
3
2
1
0
50
100
Case Temperature T
C
(
C)
150
200
V
IN
=20V, I
O
=20mA
Output Voltage V
O
(V)
0
14
12
10
8
6
4
2
0
5
10
Input Voltage V
IN
(V)
15
20
T
a
=25
C
I
O
=0A
0.2A
0.4A
Output Voltage V
O
(V)
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