72
■Features
•Compact full-mold package (equivalent to TO220)
•Output current: 3.0A
•High efficiency: 79 to 91%
•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
•Built-in soft start circuit (output ON/OFF control)
■Applications
•Power supplies for telecommunication equipment
•Onboard local power supplies
■Lineup
Full-Mold, Separate Excitation Switching Type
SI-8000S Series
Unit
V
A
°C
Symbol
VIN
IO
Tjop
Symbol
VIN
PD1
PD2
Tj
Tstg
VSW
Rth(j-c)
*SI-8033S: 35V
■Recommended Operating Conditions
■Absolute Maximum Ratings Unit
V
W
W
°C
°C
V
°C/W
Parameter
DC Input Voltage Range
Output Current Range
Operating Junction Temperature Range
Parameter
DC Input Voltage
Power Dissipation
Junction Temperature
Storage Temperature
SW Terminal Applied Reverse Voltage
Thermal Resistance(junction to case)
Ratings
43*
18(With infinite heatsink)
1.5(Without heatsink, stand-alone operation)
+125
–40 to +125
–1
5.5
Part Number SI-8033S SI-8050S SI-8090S SI-8120S SI-8150S
VO(V) 3.3 5.0 9.0 12.0 15.0
IO(A) 3.0
Ratings
SI-8033S SI-8050S SI-8090S SI-8120S SI-8150S
5.5 to 28 7 to 40 12 to 40 15 to 40 18 to 40
0 to 3.0
–30 to +125
●SI-8000S Series
73
Symbol
VO
Conditions
η
Conditions
f
Conditions
∆VOLINE
Conditions
∆VOLOAD
Conditions
∆VO/∆Ta
RREJ
Conditions
IS1
Conditions
Ratings
SI-8033S SI-8050S SI-8090S SI-8120S SI-8150S
min. typ. max. min. typ. max. min. typ. max. min. typ. max. min. typ. max.
3.17 3.30 3.43 4.80 5.00 5.20 8.55 9.00 9.45 11.50 12.00 12.50 14.25 15.00 15.75
3.234 3.30 3.366 4.90 5.00 5.10 8.73 9.00 9.27
V
IN
=15V, I
O
=1.0A V
IN
=20V, I
O
=1.0A V
IN
=21V, I
O
=1.0A V
IN
=24V, I
O
=1.0A V
IN
=25V, I
O
=1.0A
79 84 88 90 91
V
IN
=15V, I
O
=1.0A V
IN
=20V, I
O
=1.0A V
IN
=21V, I
O
=1.0A V
IN
=24V, I
O
=1.0A V
IN
=25V, I
O
=1.0A
60 60 60 60 60
V
IN
=15V, I
O
=1.0A V
IN
=20V, I
O
=1.0A V
IN
=21V, I
O
=1.0A V
IN
=24V, I
O
=1.0A V
IN
=25V, I
O
=1.0A
25 80 40 100 50 120 60 130 60 130
VIN=8 to 28V, IO=1.0A VIN=10 to 30V, IO=1.0A VIN=15 to 30V, IO=1.0A VIN=18 to 30V, IO=1.0A VIN=21 to 30V, IO=1.0A
10 30 10 40 10 40 10 40 10 40
V
IN
=15V, I
O
=0.5 to 1.5A V
IN
=20V, I
O
=0.5 to 1.5A V
IN
=21V, I
O
=0.5 to 1.5A V
IN
=24V, I
O
=0.5 to 1.5A V
IN
=25V, I
O
=0.5 to 1.5A
±0.5 ±0.5 ±1.0 ±1.0 ±1.0
45 45 45 45 45
f=100 to 120H
Z
f=100 to 120H
Z
f=100 to 120H
Z
f=100 to 120H
Z
f=100 to 120H
Z
3.1 3.1 3.1 3.1 3.1
V
IN
=15V V
IN
=20V V
IN
=21V V
IN
=24V V
IN
=25V
●SI-8000S Series
a. Part Number
b. Lot Number
c. Logo Mark
Pin Arrangement
qVIN
wSWOUT
eGND
rVOS
tS.S
Plastic Mold Package Type
Flammability: UL94V-0
Weight: Approx. 2.3g
Forming No. 1101
■External Dimensions
■Electrical Characteristics (Ta=25°C)
(unit: mm)
10.0±0.2 4.2±0.2
0.95±0.15
8.2±0.7
2.6±0.1
3.9±0.7 (4.3)
(4.6)
(8.0) (17.9)
(2.0)
0.85+0.2
–0.1
0.45+0.2
–0.1
3.2±0.2
4.0±0.2
7.9±0.2
5.0±0.6
16.9±0.3
0.5
12345
P1.7±0.7×4=6.8±0.7
2.8±0.2
φ
a
b
c
Parameter
SI-8000S*
1
Output
SI-8000SS
Voltage
Efficiency
Switching Frequency
Line Regulation
Load Regulation
Temperature Coefficient of Output Voltage
Ripple Rejection
Overcurrent Protection
Starting Current
Unit
V
%
kHZ
mV
mV
mV/°C
dB
A
*1: “S” may be indicated to the right of the Sanken logo (except SI-8120S, SI-8150S)
74
■Block Diagram
■Standard External Circuit
■Ta-PD Characteristics
2
Reg. OCP
OSC Reset
Amp.
TSD
V
REF
Comp.
Drive
1
4V
OS
V
IN
SW
OUT
GNDS.S.
53
V
IN
C
1
D
1
L
1
V
IN
V
O
GNDS.S
GND GND
SI-8000S
SW
OUT
V
OS
12
3
+C
2
+
5
4
15
20
10
5
0
–25 0 25 50
Ambient Operating Temperature Ta (°C)
Power Dissipation PD (W)
75 125100
200×200×2mm
(2.3°C/W)
100×100×2mm
(5.2°C/W)
75×75×2mm
(7.6°C/W)
Infinite heatsink
Without heatsink
With Silicon Grease
Heatsink: Aluminum
C1,2 : 1000µF
L1: 150µH
D1: RK46(Sanken)
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.
VO: Output voltage
VIN : Input voltage
IO: Output current
ηx : Efficiency (%)
VF: Diode forward voltage
0.5V(RK46)
Thermal design for D1 must be considered separately.
PD=VO•IO 100 –1 –VF•IO 1– VO
ηχ VIN
●SI-8000S Series
75
■Typical Characteristics
Output V oltage(SI-8050S) Efficiency Characteristics(SI-8050S) Load Regulation(SI-8050S)
Temperature Characteristics(SI-8050S)
Overcurrent Protection Characteristics(SI-8050S) Thermal Protection Characteristics(SI-
8050S)
Output V oltage(SI-8120S) Efficiency Characteristics(SI-8120S) Load Regulation(SI-8120S)
0
10
8
6
4
2
0246
Input Voltage VIN (V)
Output Voltage VO (V)
81012
*
Load=C.C Ta=25°C
3A
1A
I
O
=0A
Output Current I
O
(A)
Efficiency η (%)
0
100
90
80
70
60
50
00.5 1.0 1.5 2.0 2.5 3.0
T
a
=25°C
V
IN
=40V
7V
10V
20V
Output Voltage V
O
(V)
Output Current I
O
(A)
0
5.15
5.10
5.05
5.00
4.95
00.5 1.0 1.5 2.0 2.5 3.0
T
a
=25°C
10V
V
IN
=40V
7V
20V
Output Voltage V
O
(V)
–50
100
90
80
70
60
0
5.15
5.10
5.05
5.00
4.95
0
–25 0 25
Ambient Temperature T
a
(°C)
Efficiency η (%) Frequency f (kHz)
50 75 100
(V
IN
=20V,I
O
=1A)
V
O
f
η
Output Voltage VO (V)
Output Current IO (A)
0
10
8
6
4
2
0123456
T
a
=25°C
20V
40V
V
IN
=7V
Output Voltage V
O
(V)
50
10
8
6
4
2
075 100 125
Ambient Temperature T
a
(°C)
150 175 200
(VIN=20V,IO=0A)
TSD ONTSD OFF
T
a
=25°C
24V
15V
Output Current I
O
(A)
Efficiency η (%)
0
100
90
80
70
60
50
00.5 1.0 1.5 2.0 2.5 3.0
V
IN
=40V
Output Current I
O
(A)
T
a
=25°C
Output Voltage V
O
(V)
0
12.3
12.2
12.1
12.0
11.9
00.5 1.0 1.5 2.0 2.5 3.0
24V
15V
V
IN
=40V
Note on Thermal Protection:
The thermal protection cir cuit is intended for
protection against heat during instantaneous
short-circuiting. Its operation is not guaran-
teed for continuous heating condition such
as short-circuiting over extended periods of
time.
●SI-8000S Series
0
25
20
15
10
5
051015
Input Voltage V
IN
(V)
Output Voltage V
O
(V)
20 25 30
*
Load=C.C T
a
=25°C
I
O
=0A
1A
3A
76
Application Notes
1. Selecting External Components
(1) Choke coil L1
To maintain the stable operation of the regulator, choke coil L1
should be selected appropriately.
When selecting choke coil L1, consider the following:
a) Suitable for a switching regulator
Do not use a coil as a noise filter because it generates e xcess
heat.
b) Appropriate inductance
The greater the inductance of the choke coil, the smaller the
output ripple voltage. However, the size of the coil increases
large as the inductance increases. If the inductance is low, a
greater peak current flows to the IC and loss increases . This
is not favorable for stable operation.
The standard external circuit shows reference inductance val-
ues suitable for stable operation. However, the appropriate
inductance may also be calculated as follows:
L= (VIN–VO)•VO
∆IL•VIN•f
Where, ∆IL indicates the ripple current of the choke coil that
is roughly set as follows:
• If the output current is close to the maximum r ating (3 A) of
SI-8000S
Ripple current = output current × 0.2 to 0.3
• If the output current is about 1.0A or less
Ripple current = output current × 0.3 to 0.4
c) Satisfying the rated current
The rated current of a choke coil must be greater than the
maximum load current. Note that the inductance decreases
drastically and an excess current flo ws if the load current ex-
ceeds the rated current of the coil.
d) Good DC current superposition characteristics
The current flowing through a chok e coil is a triangular wa ve-
form current superimposed on a DC current equal to the load
current. The coil inductance decreases as the load current
increases. In general, the coil can be used until the induc-
tance drops to 50% of the rated v alue. Use this as the refer-
ence value f or selection.
100%
50%
I
O
(max.)
Inductance
Load current
e) Less noise
A drum-type open magnetic core coil can affect peripheral
circuits with noise because the flux passes outside the coil.
To avoid this problem, use a toroidal, EI, or EE type closed
magnetic core coil.
●SI-8000S Series
(2) Input capacitor C1
Input capacitor C1 operates as a bypass capacitor in the input
circuit.
When selecting input capacitor C1, consider the following:
a) The breakdown voltage is higher than the maximum input volt-
age.
b) Satisfies the allowable ripple current
Exceeding the ratings of this capacitor or using it without de-
rating ma y reduce its service life and also cause the regulator
to malfunction. Therefore, an input capacitor with a sufficient
margin should be selected. With the SI-8000S Series, the
eff ectiv e ripple current Irms flowing to the input capacitor can
be calculated approximately as follows:
Irms 1.2 × VO × IO
VIN
(3) Output capacitor C2
Output capacitor C2 operates as a smoothing capacitor f or switch-
ing output. The output ripple voltage from the regulator is deter-
mined by the product of the pulsating current part ∆IL (=C2 charge-
discharge current) of the choke coil current and the equivalent
series resistance ESR of the output capacitor C2.
Vrip=∆IL•C2ESR
Therefore, a capacitor of low equivalent series resistance ESR
should be selected to reduce the output ripple voltage. It is rec-
ommended to select a lo w-impedance capacitor intended for use
with s witching regulators as C2.
(4) Diode D1
Use a Schottky barrier diode for D1. If you use a gener al rectifier
diode or fast recover y diode, the IC may be damaged. (Sanken
RK46 recommended)
2. Cautions on Pattern Design
(1) Large current line
Since a large current flows through the bold lines in the standard
external circuit make the pattern as wide and as short as pos-
sible.
21
34
SI-8000S
V
IN
GND
C
1
C
2
L
1
D
1
V
OUT
GND
++
(2) Input capacitor
Place the input capacitor C1 and output capacitor C2 as close to
the IC as possible. Since a large current flows through the lead
wires of the input and output capacitors to charge and discharge
them quickly, minimize the lead wire length. The pattern around
the capacitors should also be minimized.
C
1
. C
2
.
C
1
. C
2
.
+
+
Example of bad pattern Example of good pattern
77
1. Soft Start
Connecting a capacitor to terminal no. 5 permits a soft start at power-
on. Delay time Td and rise time Ts can roughly be calculated as
shown below. (However, the values may slightly var y in an actual
application.) If the capacitance of C3 is increased, it takes longer to
discharge C3 after VIN is turned off. Therefore , it is recommended to
set the value to 10µF or less . When not using the soft start function,
keep terminal no. 5 open.
Td= 0.7×C3 (sec)
20×10–6
Ts= 4.845×C3 (sec)
VIN×20×10–6
SI-8000S
S. S.
C
3
V
IN
V
O
T
d
T
S
5
2. Output ON/OFF control
Output can be turned on and off by using the soft start ter minals.
Set the soft start terminal voltage to VSSL (0.2V typ.) or less to stop
output. To switch the potential at the soft star t ter minals, drive the
open collector of the transistor . Since the discharge current from C3
flows to the ON/OFF control transistor, limit the current for protec-
tion. The SS terminal is pulled up to the power supply in the IC and
no external voltage can be applied.
SI-8000S
S. S + ON/OFF
S. S.
5
C3
SI-8000S
S. S.
5
ON/OFF
Applications
●SI-8000S Series
(3) Sensing terminal
Output voltage sensing terminal VOS should be connected as close
to output capacitor C2 as possible. If the terminal is far from the
capacitor, the decreasing regulation and increasing switching
ripple may result in abnormal oscillation.
+
L15
VOUT
VIN GND
C1
C2
D1
SI-8000S
Example of basic pattern
Top view (with part names)
3. Variable Output Voltage
The output voltage can be increased b y connecting a resistor to VOS
terminal No. 4. (There is no way of decreasing the voltage)
(1) Variable output voltage with single external resistor
SI-8000S
2
4
V
O
'
GND
C
2
R
EX
V
S
IV
S
L
3
The output voltage adjustment resistance REX is calculated
as follows:
REX= VO'–VS
IVS
VS: Output voltage of product
VO' : Adjusted output voltage
IVS : Inflow current to Vs terminal
* The temperature characteristics of output voltage worsen because
the value REX is not compensated for temperature. The Vs value
fluctuates by up to ±20% depending on the IC product. Since the
output voltage fluctuates more, a semi-fixed resistor is necessary
for accur ate output v oltage adjustment. If Vs and REX are constant,
the range of output voltage fluctuation can be e xpressed as f ollows:
∆VO'(%)= ±20• VO'–VS
VO'
∆VO': Adjusted output voltage
(2) Variable output voltage with two external resistors
SI-8000S
2
4
VO
GND
C2
REX1
REX2
IREX1
IVS
VS
L
3
The output voltage adjustment resistances REX1 and REX2 are
calculated as follows:
REX1= VO'–VS
S•IVS
REX2= VS
(S-1)•IVS
S:Stability factor
Bypassing the current to REX2 improv es the temperature charac-
teristics and voltage fluctuation ranges more than the method of
(1). Stability factor S indicates the ratio of REX1 to Vs terminal
inflow current. Increasing the S value improves the fluctuations
of the temperature characteristics and output voltage . (Usually 5
to 10)
If the Vs and REX values are constant, the output v oltage fluctua-
tion range can be calculated as follows:
∆VO'(%)= ±20 • VO'–VS
S VO'
